LSP: add precompiles and tests

[aviatesk]

Separated from #301.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.13%. Comparing base (cc37c75) to head (12f82d8).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #310      +/-   ##
==========================================
- Coverage   69.21%   66.13%   -3.08%     
==========================================
  Files          39       39              
  Lines        3891     4072     +181     
==========================================
  Hits         2693     2693              
- Misses       1198     1379     +181     

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