Fix jena-text searches and alphabetical index restrictions by language

[osma]

Fixes #957

Comes with unit tests that verify the desired result.

[osma]

SonarCloud complains about duplicated code in tests (GenericSparqlTest and JenaTextSparqlTest have many duplicate tests, which only differ in their PHPUnit annotations). This is by design, although not ideal.

[codecov]

Codecov Report

Merging #958 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##             master    #958      +/-   ##
===========================================
+ Coverage     58.79%   58.8%   +0.01%     
  Complexity     1505    1505              
===========================================
  Files            32      32              
  Lines          4208    4207       -1     
===========================================
  Hits           2474    2474              
+ Misses         1734    1733       -1

Impacted Files	Coverage Δ	Complexity Δ
model/sparql/JenaTextSparql.php	75% <100%> (+1.22%)	15 <5> (ø)	⬇️

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[joelit]

Looks fine overall. I had some problems running the tests locally, but it doesn't seem to be related to this as everything seems to work in Travis.

[sonarqubecloud]

SonarCloud Quality Gate failed.

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
1 Code Smell

No Coverage information
64.3% Duplication