Add external greentea-client dependency ...

Use FetchContent to obtain greentea-client at version XXX.

Add extern folder for external dependencies ...

Any external libraries we depend on can be added from the "extern"
folder.

Merge pull request #14849 from arduino/pr_spif_namespace ...

SPIFBlockDevice: Add mbed namespace to BD_ERROR_DEVICE_ERROR

Merge pull request #14842 from ARMmbed/move_connectivity_lora_stubs ...

Move connectivity lora stubs

Merge pull request #14874 from LDong-Arm/optional_MBED_TEST_LINK_LIBRARIES ...

CMake: Replace `MBED_TEST_LINK_LIBRARIES` with `MBED_TEST_BAREMETAL`

CMake: Replace MBED_TEST_LINK_LIBRARIES with MBED_TEST_BAREMETAL ...

Currently we have `MBED_TEST_LINK_LIBRARIES` for specifying
* Whether to link `mbed-os` or `mbed-baremetal`
* Any additional libraries we want tests to link

It's not fit for purpose anymore, because
* No flavor of Mbed OS is selected by default, but we should've
really defaulted to `mbed-os`, the full RTOS version. Build doesn't
work unless `-DMBED_TEST_LINK_LIBRARIES=<...>` is passed, which
is redundant.
* A test should never need additional libraries passed via command
line - its `CMakeLists.txt` should specify what it links.

This commit replaces `MBED_TEST_LINK_LIBRARIES` with a new option
`MBED_TEST_BAREMETAL` to build a test with either RTOS (default)
or without it (by passing `-DMBED_TEST_BAREMETAL=ON`).

Merge pull request #14862 from LDong-Arm/storage_stubs ...

Unit tests: Move storage stubs into the storage directory

app.cmake: Replace tabs with spaces ...

The coding standards of Mbed OS require indentation of four spaces.

Merge pull request #14783 from rwalton-arm/dont_capture_stdout ...

tfm-post-build: Don't capture subprocess stdout

Merge pull request #14876 from rwalton-arm/mbed_path_greentea ...

CMake: greentea: Remove dependency on global MBED_PATH

CMake: greentea: Remove dependency on global MBED_PATH ...

The mbed_greentea_add_test macro required a greentea test to set an
MBED_PATH variable to the path of the mbed-os root directory, which it
attempts to add as a 'subdirectory' of the test project. We can instead
use CMake's built in CMAKE_CURRENT_LIST_DIR variable to deduce the path
to mbed-os relative to the current list file directory, removing the
need for greentea tests to set MBED_PATH.

Merge pull request #14875 from saheerb/cloud-example-enable ...

enable google and azure example application tests in ci

Merge pull request #14864 from AnishKumarHCL/analogout_free_code_alignment ...

analogout: STM32: modified analogout_free api

CMake: greentea: Remove call to deprecated function ...

mbed_greentea::mbed_greentea_add_test was calling the deprecated
`mbed_configure_app_target` function, which is currently a no-op.

enable google and azure example application tests in ci

analogout: STM32: modified analogout_free api ...

removed hardcoded pins, implemented multi channel check
implemented DAC_2 initialization for H7 board
Added  #if defined DAC_CHANNEL_2

Unit tests: Remove mbed-headers-storage

Unit tests: Create mbed-headers-kvstore ...

Create a CMake target mbed-headers-kvstore to separate KVStore headers
from the generic mbed-headers-storage. Update tests to use it.

Unit tests: Create mbed-headers-filesystem ...

Create a CMake target mbed-headers-filesystem to separate FileSystem
headers from the generic mbed-headers-storage. Update tests to use it.

Unit tests: Create mbed-headers-blockdevice ...

Create a CMake target mbed-headers-blockdevice to separate BlockDevice
headers from the generic mbed-headers-storage. Update tests to use it.

Unit tests: Limit storage stubs to link what it uses

Unit tests: Do not include mbed.h in storage stubs ...

The header `mbed.h` pulls in headers from a number of Mbed OS
components that are not necessarily used. It was intended for user
applications only, and libraries and unit tests should explicitly
include library headers it uses to limit dependencies.

This change avoids having to link unnecessary libraries in storage
unit tests' CMake definitions.

Move storage stubs into subdirectories of Mbed OS storage ...

Move storage stubs from UNITTESTS/stubs into components inside the
top-level storage directory. Specifically,
* storage/blockdevice/tests/UNITTESTS/doubles/ for BlockDevice stubs.
* storage/kvstore/filesystemstore/tests/UNITTESTS/ for a stub used by
the FileSystemStore test. The stub has been renamed from
kv_config_stub.cpp to filesystemstore_kv_config_stub.cpp, to make it
evident why it doesn't go into storage/kvstore/kv_config/.

CMake: storage: Remove trailing whitespaces

Unit tests: Remove unused EmulatedSD

CMake: Move lorawan stub headers to the lorawan/tests/UNITTESTS/double dir ...

Previously all the lorawan stubs headers under mbed-stubs-headers,
so this PR move all lorawan stubs headers under
cellular/tests/UNITTESTS/double directory and update CMake to include
stubs headers into mbed-stubs-lorawan library to make lorawan stubs to be self-contained

CMake: unit-tests: Make lorawan stub only depend on headers it uses ...

Previously the connectivity lorawan stub library depended on
`mbed-headers`, which is a collection of all available headers
in mbed-os. To make it easier to separate the library, only depend
on the headers we're using.

CMake: Update lorawan unittest to use mbed-headers-lorawan lib ...

Update lorawan unit test to link only with a mbed-headers-lorawan
library that it depends on instead of link with mbed-headers
which is a group of headers libraries.

CMake: unit-tests: Add mbed-headers-lorawan headers library ...

Previously, all lorawan headers made as a part of the
mbed-headers-connectivity library. To make it easier to separate all
the lorawan headers into the separate mbed-headers-lorawan library
and keep them, as part of lorawan stubs CMake. This makes the lorawan
stubs more self-contained and improves the composition of the library.

CMake: Update lorawan unittest to use mbed-stubs-lorawan ...

Update lorawan unit test to link only with a mbed-stubs-lorawan
library that it depends on instead of link with mbed-stubs
which is a group of stubs libraries.