Simplify CMake config and optimize includes

[RobinTF]

In particular:

• Clean up the usage of the FETCH_CONTENT module by using its builtin functionality instead of manual hacks (see the JSON and ANTLR dependencies for details).
• Make the includes of the ANTLR and ABSL submodules (which use macros that collide with our own) more robust.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.25%. Comparing base (77ac964) to head (9937811).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1618      +/-   ##
==========================================
+ Coverage   89.24%   89.25%   +0.01%     
==========================================
  Files         374      375       +1     
  Lines       35315    35315              
  Branches     3988     3988              
==========================================
+ Hits        31518    31522       +4     
+ Misses       2503     2501       -2     
+ Partials     1294     1292       -2     

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[joka921]

An initial feedback.
It might be, that we throw out again FetchContent in the near future (for reasons),
But that is for another discussion.

Alsom, in the macos workflow it says env.build-type once, and matrix.build-type twice. It has to be always env.build-type, thant is the issue there.

[RobinTF]

@joka921

Alsom, in the macos workflow it says env.build-type once, and matrix.build-type twice. It has to be always env.build-type, thant is the issue there.

I'm pretty sure you mean it has to be matrix.build-type

[sparql-conformance]

Conformance check passed ✅

No test result changes.

Details: https://qlever.cs.uni-freiburg.de/sparql-conformance-ui?cur=99378114e056076f2ffb7fc5071fed612d2e0c77&prev=77ac964e9de37c10142bc19735d19fbb0c02ccc6

[sonarqubecloud]

Quality Gate failed

Failed conditions
D Maintainability Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

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