docs: Update the list of CMake options

[nurupo]

• Sorted
• Added missing FLAT_OUTPUT_STRUCTURE
• Added missing PROXY_TEST
• Removed no longer existing EXECUTION_TRACE
• Updated some option descriptions and made them match CMakeLists.txt

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This change is 

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 73.19%. Comparing base (77e0887) to head (e71a68b).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2710 +/- ## ========================================== + Coverage 73.05% 73.19% +0.14% ========================================== Files 149 149 Lines 30517 30517 ========================================== + Hits 22293 22337 +44 + Misses 8224 8180 -44 ```

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