Feature: Reintroduce FetchContent

[sandro-elsweijer]

Closes #2304

Describe your changes here:
Reintroduces FetchContent after its removal in #2289

Improvements in this PR:

• MakeAvailable was called multiple times for each target
• Renamed dependencies to thirdparty, because not all libs in fetchcontent are mandatory
• Combined fixes for SC and GTest
• Fixed Gtest fix for Windows systems
• Fixed CI
• Marked some variables as internal instead of advanced
• removed git_progress, because the output was too long and cmake truncated it

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.57%. Comparing base (7c121bf) to head (2b91986).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2303   +/-   ##
=======================================
  Coverage   82.57%   82.57%           
=======================================
  Files         116      116           
  Lines       18553    18553           
=======================================
  Hits        15320    15320           
  Misses       3233     3233           

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[benegee]

Awesome!

From what I can tell, this looks good so far!

[benegee]

LGTM!