Some non-Mbed-OS, pre-existing CMSIS-RTOSv2 applications depend on
CMSIS-RTOSv2 Automatic Dynamic Allocation, also known as Object-specific
memory pools. Mbed OS doesn't by default provide any memory to the
CMSIS-RTOSv2 Automatic Dynamic Allocation pool, as doing so would waste
memory if the feature is not used; even if the feature is used, as a
platform, Mbed OS can't know how many objects of which types will be
created by an application and therefore will either waste memory or not
provide enough memory in a hard to debug manner. Portable CMSIS-RTOSv2
applications depending on CMSIS-RTOSv2 Automatic Dynamic Allocation
should instead configure the memory pools themselves, as applications
know best their memory requirements.

Add Mbed configuration options which can be used by applications to
control the amounts of memory available to the CMSIS-RTOSv2 Automatic
Dynamic Allocation subsystem. This enables portable CMSIS-RTOSv2
applications, which can run on any CMSIS-RTOSv2 OS, to be able to run on
Mbed OS as well.

RTX's configuration options for CMSIS-RTOSv2 memory are documented at
http://www.keil.com/pack/doc/CMSIS_Dev/RTOS2/html/config_rtx5.html

Signed-off-by: Devaraj Ranganna <devaraj.ranganna@arm.com>
Signed-off-by: Jaeden Amero <jaeden.amero@arm.com>