feat(memory-map) allow fixed static ram and heap size boundaries (IDFGH-858)

[GautierAtWork]

Currently the heap size is defined at link time as "the remaining ram", what is not deterministic.

Once the product is released, and a minor revision is created, it should be ensured that critical parameters of the system are not impacted.
With a non deterministic heap size, no one can guarantee that connectivity is not impacted by any code change, even a minimal innocent one.

This patch makes the static ram size configurable from Kconfig, and indirectly fixed the heap size. Any change of the heap size is fully under control.

[negativekelvin]

The runtime heap allocator does not use _heap_start it only uses _bss_end so this may have no effect on heap size and only restrict dram0_0_seg length

[GautierAtWork]

@negativekelvin Thanks for that. Seems it changed since the ESP-Idf version we are using.
I will have a look.

[GautierAtWork]

@negativekelvin: fixed

[projectgus]

Hi @GautierAtWork ,

This seems like a good addition for increasing determinism of resource use. A couple of small notes, but mostly LGTM.

[igrr]

Thank you for the PR @GautierAtWork, and apologies for the late review. Just a couple of cosmetic comments.

Also, can you please combine the commits into one and rebase onto master? Thanks.

[projectgus]

Thanks for contributing this, @GautierAtWork . Thanks also for being patient while we worked through the review process.

I've squashed these commits into one and pushed them into our internal review & merge queue. The PR will be updated once the changes are merged and pushed to GitHub.

[igrr]

Thanks for the PR @GautierAtWork, it has been cherry-picked as 542e544.