mbed-ce@master + fixes + gcc 11 support (#135) ...

* Fix rtos::Mutex stub, add trylock() method

* LowPowerTicker - Add ::attach(...) method + call callback

* mbed_power_management - rename sleep --> mbed_sleep to avoid conflicts

Fixes conflicts w/ unistd.h and boost::ut

* GCC 11/C++ 20 - Remove deprecated type_traits

* GCC 11/C++ 20 - Remove redundant templating of methods

* Warning - pragma ignore invalid-noreturn for unit tests

* Fix astyle errors

* Fix missing mbed_sleep() calls

Fix some build errors

Unit tests: Add boilerplate code for AnalogIn.cpp ...

In pursuit of increasing unit test coverage of Mbed OS, we add the
boilerplate code for unit testing of AnalogIn.cpp and an empty test
source file. This serves two purposes - it allows us to report on
currently untested sources in code coverage data, and it makes it a
little easier for developers to write unit tests for these sources.

The 'empty' test file contains a main function that simply returns. This
is required to allow CMake's add_executable() to be used to pull in the
source file for the SUT, which ensures that this source file is built
and therefore instrumented to generate coverage data. The alternative
that was explored was to instead use Google Test's TEST() macro and
prefix the test name with 'DISABLED_' to skip it, but that resulted in
the test being reported as skipped, which was deemed undesireable for
these 'empty' tests.

Unit tests: Remove redundant CMake target mbed-headers-base ...

Individual libraries' `target_h` stub headers have now all been moved
from `mbed-headers-base` to `mbed-headers-<library>`.

Note: Even though headers previously in `target_h` are technically
stubs/fakes too, they are used by not only unit tests but also regular
libraries when compiled for unit tests, because no target-specific HAL
implementation exists in this case. In order for regular library
sources to pick up `target_h` headers, those headers must

* have the same names as regular headers
* appear first in include paths

This is why those headers are part of `mbed-headers-<library>` and not
`mbed-stubs-<library>`. Before this refactoring, `mbed-headers-base`
was the first in unit tests' include paths.

Unit tests: Move drivers target_h stubs

CMake: unittests: Show all tests in CTest report ...

Previously a test executable was recognised as a single test by CTest.
However, test executables usually contain multiple test cases, the
results of the test cases should be individually reported. With our
previous setup we could miss test case failures that didn't cause the
executable to return an error code.

This commit uses gtest_discover_test to discover all test cases in a
test executable. This enables CTest to match test passes and failures
from the googletest binary output.

CMake: unittests: Remove trailing whitespace

Merge pull request #14786 from ARMmbed/move_drivers_stub ...

Move mbed-stubs-drivers to the drivers directory

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

Previously the drivers 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: unit-tests: Move mbed-headers-drivers to the drivers directory ...

Move the header-only mbed-headers-drivers library the unit test stubs
depend on into the drivers component directory. This makes the drivers
stubs more self-contained and improves the composition of the library.

CMake: Move drivers stubs to the mbed-os/drivers directory ...

Move the drivers stub library into the drivers component directory.
so we can avoid duplicating the mbed-os source tree in a central
UNITTESTS folder.

CMake: unit-tests: Make drivers UNITTESTS only depend on headers it uses ...

Previously the drivers unit tests 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: unit-tests: Pwmout & Watchdog: Remove trailing whitespace

CMake: Remove all unittest.cmake script from test suite ...

- Remove redundant cmake script as already added the CMake configuration file
- Remove redundant empty_baseline as it is no longer needed with the help of CMake configuration file

CMake: Refactor drivers unittest cmake

Move SFDP unit tests

Initial unit test for SFDP ...

As a starting point, only sfdp_iterate_next_largest_erase_type(),
which the pull request is intended to fix, is tested. More test
cases shall be added in the future.

Move drivers unit tests