Only support GCC ARM compiler, but reap the benefits of static libraries instead of objects

- 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

CMake: greentea: Fix io issue with greentea-client ...

The stdio implementation of the standalone greentea-client wasn't
streaming "KiVi protocol" messages through the serial IO. Separate out
the existing implementation for greentea-client that uses
mbed_retarget.h's `read` and `write` functions so greentea tests
continue to work with the standalone client.

The IO fixture is shared between the "legacy" embedded greentea-client
and the newer standalone client.

Use standalone greentea-client ...

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

CMake: Create mbed-greentea library

CMake: Rename CMake targets ...

* mbed-os renamed mbed-core
* mbed-os-<COMPONENT> renamed mbed-<COMPONENT>

CMake: Componentize Mbed OS into multiple CMake targets (#13732) ...

Aside from the core mbed-os CMake target, a number of targets have been created so they can optionally be included by application executables that require them using `target_link_libraries()`.

Co-authored-by: Martin Kojtal <martin.kojtal@arm.com>
Co-authored-by: Rajkumar Kanagaraj <rajkumar.kanagaraj@arm.com>

CMake: Fix build failure due to mbed-trace, mbed-client-randlib, and nanostack dir changes

CMake: Fix failures due to device_key and storage dirs move

CMake: Fix build failure due to lora, cryptocell, and nfc dirs move

CMake: Fix failure due to MbedTLS rdir relocation

CMake: Fix build failure due to nanostack dir move

CMake: Fix build failure due to drivers and lwipstack dirs move

CMake: Fix failure due to events and netsocket dirs changes

CMake: Fix build due to system_storage and netsocket dir move in master

CMake: Fix failure due to kvstore and cellular dirs changes

CMake: Add support for features dir