Fix REPLACE function with replace patterns

[RobinTF]

In the replace string of the REPLACE function, QLever now uses a dollar sign $ to dynamically fetch the replacement from the input. For example REPLACE("aabc", "(a+)b", "$1def$1") will now correctly result in "aadefaac".
This fix is implemented by manually converting the replacement string to the format the Google RE2 expects where the replacement format is not $n but \n.
Fixes #1664

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.01%. Comparing base (db6825c) to head (69b38ae).
Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1755      +/-   ##
==========================================
+ Coverage   89.98%   90.01%   +0.02%     
==========================================
  Files         395      395              
  Lines       37693    37779      +86     
  Branches     4241     4256      +15     
==========================================
+ Hits        33919    34005      +86     
  Misses       2478     2478              
  Partials     1296     1296              

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[joka921]

I have left two and a half comments, that should be easy to address.

[sparql-conformance]

Conformance check passed ✅

Test Status Changes 📊

Number of Tests	Previous Status	Current Status
1	Failed	Passed

Details: https://qlever.cs.uni-freiburg.de/sparql-conformance-ui?cur=69b38ae54f00f5ee92627b7dbf52aa2b759a18c6&prev=be240abc3bc9bfa731353d612c3db4c2187bba41

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud