Create working cmake files for examples (version 2)

[Yarik-Popov]

Purpose

• Add working cmakelists for example files

• This PR replaces Create working cmake files for example files #259 as that one had way too many merge conflicts to deal with.

• Notion task: https://www.notion.so/uworbital/6375c5c5dcf1485e8a6c47f18d419ae5?v=72baf90d01f643b09d77418bd3f53b14&p=062e93d0a1b54c608dcdf98fa46a720c&pm=s

New Changes

• Added Examples build option in top-level directory CMakeLists
• Added options in obc/CMakeLists to build specified example in obc/examples
• Added instructions for how to build an example in README
• Make -Werror only apply for OBC build (test that it still errors on warnings by adding unused variables)
• Move and separate tests under comms_link_mgr to examples
• Delete unused makefiles in examples

Testing

• Commented out initLogger() function from test_app_rtc/main.c
• Manually build all the example files from obc/examples with new CMakeLists.

Outstanding Changes

• Make -Werror apply to all example builds once all example builds are fixed
• Make obc github workflows independent for each board
• Fix errors from example source files. Listed here:
• test_app_fram_persist, test_app_rs has unresolved warnings.
• test_app_freertos_posix has unresolved warnings and source file errors.
• test_app_mpu6050, test_app_cc1120_spi has source file errors.
• test_app_rtc - location of initLogger is changed so need update from source file.
• test_app_fram_spi, test_app_reliance_edge_sd, test_app_uart_rx, test_app_uart_tx, dma_spi_demo has no errors.

[github-actions]

Pull reviewers stats

Stats of the last 120 days for UWOrbital:

	User	Total reviews	Time to review	Total comments
	Yarik-Popov	11	9d 20h 58m	116
	kepler452b123	5	9h 15m	32
	Navtajh04	4	12h 6m	28
	dgobalak	3	7h 41m	15
	Gjjjiang	1	35d 1h 57m	1

^{⚡️ Pull request stats}

[Yarik-Popov]

Clarification on -Werror comment

[Yarik-Popov]

Handling adc and other examples that were merged recently

[dgobalak]

low risk so lgtm as long as the examples build correctly. I'll let navtaj approve

Handled

[Navtajh04]

Wait for examples check to finish before merge

[Yarik-Popov]

All examples built so merging in