Fine tune the managed heap size definition on reference targets

[nfbot]

From nf-interpreter created by josesimoes : nanoframework/nf-interpreter#366

The current definition of the managed heap size (clr_managed_heap_size in each targets\CMSIS-OS\ChibiOS\TTAARRGGEETT_BBOOAARRDD\CMakeLists.txt) is not optimal and for most boards is kind of short.

It's already optimized for Discovery4 target in nanoframework/nf-interpreter#365.
Need to go through the remaining target boards and maximize the size of it.
Suggest that the CRT heap is moved to the CCM (on the targets were available). This happened in #365 for Discovery4 too.

On the boards were the CRT heap shares the same RAM region, make sure the Managed Heap size leaves a fair amount of RAM to the CRT heap.

[josesimoes]

This has been addressed in nanoframework/nf-interpreter#528.
Instead of optimizing the size of the managed heap, it was made completely automatic in the linking stage.