RTOS API for bare metal ...

Provide partial RTOS API for bare metal builds - things that
can be done in a single threaded environment.

Allows more code to work in both RTOS and bare metal builds without
change, and in particular gives easy access to the ability to
efficiently wait for something occurring in interrupt.

Available in bare-metal:
* ThisThread
* osThreadFlagsSet to set flags on main thread (can be set from IRQ)
* EventFlags (can be set from IRQ)
* Semaphores (can be released from IRQ)
* Mutex (dummy implementation)

Not useful:
* ConditionVariable (could only be signalled from 2nd thread)
* RtosTimer (calls in a second thread context)
* Thread

Unimplemented:
* Mail, Queue, MemoryPool

Possible future work:
* ConditionVariableCS to act as IRQ signalled ConditionVariable

mem pool size: Fix calculation of memory pool size for portability ...

Replace the hardcoded value calculation of the memory pool block size
with the RTX preprocessor macro (via a shim layer).
This is in preparation for the replacement of the direct access of RTX
functionalities in Mbed OS with an access via CMSIS.

Merge pull request #10225 from kjbracey-arm/memorypool_blocking_alloc ...

Mail/MemoryPool: blocking alloc

Mail/MemoryPool: blocking alloc ...

Mail and MemoryPool did not permit access to the blocking form of
allocation available in CMSIS-RTOS 2 - give them new blocking methods.

RTOS API: minor tidies ...

Remove unneeded memsets and an unneeded cast.

Add missing initialisation of EventFlags attributes - no all fields were
being initialised.

rtos: fix astyle

Copy edit MemoryPool.h ...

Copy edit file for active voice.

Add notes about ISR safety to RTOS doxygen

Merge pull request #5372 from SenRamakri/sen_PlatformDoxygenUpdates ...

Doxygen comments fixes

Shrink RTOS classes ...

Various RTOS classes were storing their CMSIS-RTOS creation attribute
structure as a member, when it's not required after construction. Reduce
memory by eliminating this member.

Doxygen comment updates and fixes

Fix pool buffer size, update free() description, add assertion in MemoryPool.h header file. ...

Provide fix for pool buffer size: pool block size must be
a multiple of 4 bytes.
Add assertion to forbid creation of MemoryPool object with queue size equal to 0.
Update description of free() function. Add information about
statuses returned by this function.

Merge pull request #4601 from pan-/fix_memory_pool_destructor ...

rtos: Fix MemoryPool and Queue destructor

rtos: Add missing destructor for MemoryPool objects.

rtos: Tag non value type as NonCopyable. ...

The types marked are: Mail, MemoryPool, Mutex, Queue, RtosTimer and Semaphore.

Resolve Doxygen errors from RTOS. Fixed minor Doxygen bug in FileSystemHandle.h as well

Make sure all RTOS attribute structures are 0-ed before use

Update codebase for CMSIS5/RTX5 ...

Update all of mbed-os to use RTX5.

Add tags to our code

restructure - Restructured rtos directory