Implement more GSP features

[Qup42]

• Implement the HEAD operation. Closes ad-freiburg/qlever-private#63
• Correct response status code for PUT. Closes ad-freiburg/qlever-private#61
• Implement POST where the server creates a new graph. Note: the chosen graph is not guaranteed to not exist before. An intermediate solution could be to generate the graphs with a prefix and a counter. Knowing which graphs exist is a more involved task. Closes ad-freiburg/qlever-private#75

Open questions:

• https://github.com/w3c/rdf-tests/blob/main/sparql/sparql11/http-rdf-update/manifest.ttl#L32 - why is it supposed to return 200? The referenced graph is never created.

[Qup42]

Note: this might (though probably more in theory than in practice) generate the same graph twice making it incorrect. Keeping tracks of all graphs and/or explicit graph existence would go beyond the scope of this PR. As an intermediate solution the graphs will be generated with the internal prefix and a counter.

[Qup42]

TODO

[codecov]

Codecov Report

❌ Patch coverage is 38.50000% with 123 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.88%. Comparing base (6ee3a75) to head (3b83158).
⚠️ Report is 32 commits behind head on master.

Files with missing lines	Patch %	Lines
src/engine/GraphManager.cpp	14.03%	49 Missing ⚠️
src/engine/Server.cpp	0.00%	21 Missing ⚠️
src/engine/GraphStoreProtocol.cpp	41.17%	20 Missing ⚠️
src/util/http/ResponseMiddleware.h	5.88%	16 Missing ⚠️
src/engine/GraphStoreProtocol.h	77.14%	8 Missing ⚠️
src/util/http/HttpUtils.h	75.00%	6 Missing and 2 partials ⚠️
src/engine/SparqlProtocol.cpp	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2532      +/-   ##
==========================================
- Coverage   91.11%   90.88%   -0.23%     
==========================================
  Files         466      471       +5     
  Lines       39777    40245     +468     
  Branches     5320     5389      +69     
==========================================
+ Hits        36242    36576     +334     
- Misses       2024     2139     +115     
- Partials     1511     1530      +19     

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[sparql-conformance]

Overview

Number of Tests	Passed ✅	Failed ❌	Intended ⚠️	Not tested
458	382	76	0	0

Conformance check failed ❌

Test Status Changes 📊

Number of Tests	Previous Status	Current Status
1	Passed	Failed
4	Failed	Passed

Details: https://qlever.dev/sparql-conformance-ui?cur=3b83158296504374352ef17f50aa3d35bf4b07cc&prev=562396cc756734eaa6c24037373d7a911402270d

[sonarqubecloud]

Quality Gate passed

Issues
12 New issues
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