De-duplicate boardinglocations on areas

[MaxGosau]

Summary

when two stops reference the same OSM platform area (via ref:IFOPT), only one OsmBoardingLocationVertex centroid is created for that area and both stops are linked to it. This ensures that transfers on the same platform can always be reached (0-min transfers).

Issue

the issue was previously discussed here: #7240
this PR implements the "Quick fix" outlined by Jessica

The Sollution uses a simple HashMap to ensure that only one OsmBoardingLocationVertex gets created for each stop connected to an area.

This will have an impact on all transfers using the same OSM Area
Before:

After:

The main difference being, that there is no longer a footpath in the resulting itinerary (instantaneous transfer).

Some minor refactorings to OsmBoardingLocationsModule were also added in a seperate commit: (Refactor OsmBoardingLocationsModule for simplicity)

Unit tests

One of the existing unit test cases uses an example in Herrenberg, which already included an OSM area with 2 stoppoints, so only a new testcase was added, to verify the de-duplication

Documentation

• javadoc added on factory method and test

[codecov]

Codecov Report

❌ Patch coverage is 96.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 71.32%. Comparing base (1158ac0) to head (514f5f9).
⚠️ Report is 26 commits behind head on dev-2.x.

Files with missing lines	Patch %	Lines
...aph_builder/module/OsmBoardingLocationsModule.java	96.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             dev-2.x    #7508      +/-   ##
=============================================
+ Coverage      71.02%   71.32%   +0.29%     
- Complexity     21002    21146     +144     
=============================================
  Files           2352     2357       +5     
  Lines          87266    87552     +286     
  Branches        8635     8660      +25     
=============================================
+ Hits           61983    62446     +463     
+ Misses         22293    22101     -192     
- Partials        2990     3005      +15     

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[jessicaKoehnke]

Maybe it would be better to use the Platform as a key in the map, then the deduplication can also be used for edges. Or is there a reason not to do that?