Fix assertion failures missed from test log when multiple tests fail

- Split mbed-core and mbed-rtos into -sources and -flags targets ...

- Fix some logic errors in top level cmakelists related to building greentea tests
- Fix mbed_create_distro() for OBJECT libraries

Use standalone greentea-client ...

For CMake or Mbed CLI 2, use the standalone greentea-client.

CMake: Create mbed-greentea library

Change MBED_STATIC_ASSERTs version for built-in

Add SPDX license identifier to Arm files ...

Add license identifier to files which Arm owns the copyright to,
and contain either BSD-3 or Apache-2.0 licenses. This is to address
license errors raised by scancode analysis.

Use std::chrono based functions ...

The chrono based functions improve readability. Using them also removes
warnings related to usage of deprecated warnings.

Tests: Remove support for ARM Compiler 5 ...

ARM Compiler 5 is no longer actively supported and was superseded in
Mbed OS by ARM Compiler 6.

Remove the deprecated Ticker APIs

Replace RawSerial instances as it has been deprecated

Can compile without serial

Update utest README

Removing references to yotta and minar within utest

Framework: Add required header file and namespace element instead add all

Unity: Add macros for test skipping. ...

The TEST_SKIP and TEST_SKIP_UNLESS macros (w/ and w/o messages) allow the test
to skip the test case execution from the point the macro was called (without
failing the test).

Added copyright header to all tests

Add support for runtime test specification ...

Add a constructor which explicitly takes the number of test cases.
This allows a test case array created at runtime to be used.

Placed verbatim tags around a pair of brackets that Doxygen interpreted as xml tags

Resolved Doxygen build errors

utest_case.h : Fix comment indentation

utest case: Indicate explicitely that no data member shall be declared in ...

the Case class.

utest optimization: Allow case data structure to be put in ROM. ...

This patch split the Case class in two entities: Case and case_t. case_t contains the test case data structure while Case provide the interface to the test case. Unlike the class Case, case _t is a POD and can be instantiated at compile time and put in the constant data section (in ROM).

The Specification class has also been modified to accept arrays of case_t.

Renamed files in platform to match source names ...

critical.h     -> mbed_critical.h
sleep.h        -> mbed_sleep.h
toolchain.h    -> mbed_toolchain.h
rtc_time.h     -> mbed_rtc_time.h
semihost_api.h -> mbed_semihost_api.h
wait_api.h     -> mbed_wait_api.h

Add tags to our code

UTEST - Fix warning by removing unreachable statement. ...

Some compiler will trigger warnings if code is located after the exit function
because this function never returns (by the standard...).

UTEST - Fix warning in utest_shim.cpp by removing unreachable statement.

Add stack metrics to greentea ...

Update greentea to report thread information when a thread exits or
is terminated and when testing completes. Also move metrics into
a dedicated greentea file.

Use SingletonPtr for the internal variables defaults and handlers in utest_harness.

Use a SingletonPtr for the Timeout object in utest_shim. ...

Makes sure to initialize it, otherwize, it might be initialized in
interrupt context.

Improve compatibility between base_control_t and control_t. ...

* provide missing member functions from control_t in base_control_t
* construction of control_t from reference of base_control_t instead of
  value.
* overload operator+ for all permutations between control_t and
  base_control_t.