Extend rebuild-index to hot swap the existing index after completion

[RobinTF]

DRAFT PR, contains bugs. Handle with care.

The text index doesn't currently work with this and materialized views do also not work. And there might be some race conditions when actually swapping the index.

[codecov]

Codecov Report

❌ Patch coverage is 77.12418% with 35 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.37%. Comparing base (eeb9fd0) to head (012fea9).
⚠️ Report is 13 commits behind head on master.

Files with missing lines	Patch %	Lines
src/engine/Server.cpp	73.80%	29 Missing and 4 partials ⚠️
src/engine/Server.h	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2832      +/-   ##
==========================================
- Coverage   92.38%   92.37%   -0.02%     
==========================================
  Files         506      506              
  Lines       43998    44060      +62     
  Branches     5824     5826       +2     
==========================================
+ Hits        40649    40699      +50     
- Misses       1697     1703       +6     
- Partials     1652     1658       +6     

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[sparql-conformance]

Overview

Number of Tests	Passed ✅	Intended ✅	Failed ❌	Not tested
548	447	73	28	0

Conformance check passed ✅

No test result changes.

Details: https://qlever.dev/sparql-conformance-ui?cur=012fea9d72621999eaea5dc42261efcce4335e61&prev=eeb9fd046af37ed2ade22b824a32e936493ee7f3

[sonarqubecloud]

Quality Gate passed

Issues
8 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