refactor: Simplify and rename SipiService

[seakayone]

Pull Request Checklist

Task Description/Number

Issue Number: NO-TICKET

Removes GetFileMetadataRequest and respective GetFileMetadataResponse using the response from Sipi instead.

PR Type

• build/chore: maintenance tasks (no production code change)
• docs: documentation changes (no production code change)
• feat: represents new features
• fix: represents bug fixes
• perf: performance improvements
• refactor: represents production code refactoring
• test: adding or refactoring tests (no production code change)

Basic requirements for bug fixes and features

• Tests for the changes have been added
• Docs have been added / updated

Does this PR introduce a breaking change?

• Yes

Does this PR change client-test-data?

• Yes

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (ff9df5f) 11.63% compared to head (937e76f) 88.48%.
Report is 2 commits behind head on main.

Files	Patch %	Lines
.../org/knora/webapi/store/iiif/api/SipiService.scala	66.66%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2929       +/-   ##
===========================================
+ Coverage   11.63%   88.48%   +76.84%     
===========================================
  Files         247      246        -1     
  Lines       22922    22906       -16     
===========================================
+ Hits         2668    20268    +17600     
+ Misses      20254     2638    -17616     

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