[Gen 3] stack size fixes, __cxa_acquire/release/atexit refactoring

[avtolstoy]

Problem

Gen 3 platforms trigger a hardfault on boot with #2840 every other time.

Solution

1. Increase main stack size for Gen 3 platforms from 2K to 4K
2. Add asserts to linker files to make sure that stack sizes match the expected values
3. atexit is not needed for our platforms, so it's now stubbed out freeing additional flash space of unneccassary destructor implementations
4. __cxa_acquire/__cxa_release do not account for thread-safety, the implementation has been refactored.
5. Panic handler should not log anything, as that may trigger a secondary fault making debugging more difficult and causing a lock-up instead of a reset

Steps to Test

#2840 cloud test app

Example App

N/A

References

N/A

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Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[sergeuz]

Looks good 👍