Memory pool

[n1LS]

Before:

FLASH:      714524 B         2 MB     34.07%
  RAM:      233704 B       256 KB     89.15%

After:

FLASH:      713948 B         2 MB     34.04%
  RAM:      230328 B       256 KB     87.86%

[n1LS]

Implements #1284

[maks]

@n1LS thanks for working on this!
As a starting point could you add some explanation of what you have done here. Is this only for consolidating existing file index lists or does it go further than that, etc

[n1LS]

@maks Sorry, I missed you message.

This pr implements pretty much exactly what's described in the issue:

1. It adds a MemoryPool implementation that shares a 1kB RAM buffer, that is freely available for short-term use. A few parts of the firmware had local buffers that were deemed to big to be heap allocated, but only used rarely (as string buffers) etc. I removed those statically allocated buffers and some heap allocations of the same sort.
2. The shared memory is protected via the Acquire() and Release() functions, leading to visual warnings in DEBUG builds, when an access occurs on the locked buffer.
3. I unified the various etl::vector<int, MAX_FILE_INDEX_SIZE> fileIndexList across all views to use a static one provided by the MemoryPool.

Next steps:

This already improves RAM usage by 3.376 Bytes (1.3%) and there's still a few static memorty allocartions that could be moved to the MemoryPool. Those should be identified and updated.

[maks]

thanks for working on this @n1LS . I left some feedback and also this needs to be brought up to date with master branch.

[n1LS]

@maks I added mutexes to prevent multiple access via scoped locks, which are held/release with the scope of the buffer/fileIndexList received

[maks]

@n1LS can you please resolve merge conflicts