Tests: Add Zephyr System Tests

[SorinOlari]

Description

• Added Zephyr system tests support
• Added Zephyr system tests to the CI

Also, please list any issue that this PR is intended to fix.

• Fixes issue # zephyr: add system tests to native_sim #158

Type of change

Please delete options that are not relevant.

• This change requires a documentation update
• CI system update
• Test Coverage update

How Has This Been Tested?

• locally on native_sim_64
• CI

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[kr-t]

note: rebasing via web in order to merge w ff

[kr-t]

np: Maybe in the future, to avoid this many board configs for the same board, we would want to use build system variables, and either pass the (one and only) board test config via west or CMake. Please check: https://docs.zephyrproject.org/latest/develop/application/index.html#important-build-system-variables