Validate stop id in Transit leg reference

[vpaturet]

Summary

As detailed in #5423, transit leg references currently refer to stop position, not stop id: if the trip pattern is changed by a real-time update, the leg reference could point to the wrong physical stop.

This PR verifies that the referenced stop positions still refer to the same stop ids in the actual pattern.
As an exception, the reference is considered valid if the referenced stop is different but belongs to the same parent station: this covers for example the case of a last-minute platform change in a train station that typically does not affect the validity of the leg.

This PR modifies the structure of the serialized leg id by adding new fields, but guarantees that existing (legacy) references will be deserialized successfully.

Issue

Partially addresses #5423

Unit tests

Added unit tests

Documentation

No

[codecov]

Codecov Report

Attention: 15 lines in your changes are missing coverage. Please review.

Comparison is base (c44b66c) 66.67% compared to head (562609b) 66.81%.
Report is 75 commits behind head on dev-2.x.

Additional details and impacted files

@@              Coverage Diff              @@
##             dev-2.x    #5440      +/-   ##
=============================================
+ Coverage      66.67%   66.81%   +0.13%     
- Complexity     15396    15470      +74     
=============================================
  Files           1794     1798       +4     
  Lines          69683    69808     +125     
  Branches        7345     7360      +15     
=============================================
+ Hits           46462    46641     +179     
+ Misses         20758    20711      -47     
+ Partials        2463     2456       -7     

Files	Coverage Δ
...pentripplanner/model/plan/ScheduledTransitLeg.java	90.57% <100.00%> (+0.13%)	⬆️
...nner/model/plan/legreference/LegReferenceType.java	88.88% <77.77%> (+11.96%)	⬆️
...lan/legreference/ScheduledTransitLegReference.java	81.66% <77.27%> (-2.55%)	⬇️
...odel/plan/legreference/LegReferenceSerializer.java	63.15% <57.89%> (-9.92%)	⬇️

... and 29 files with indirect coverage changes

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[leonardehrenfried]

Please have a look at my comments.

[vpaturet]

Added a more robust versioning logic. This will make it easier to implement further modifications in the leg serialized id structure

[t2gran]

The design is a bit awkward. But, we can leave it for now. I would love to make a common TokenSerializer witch encapsulate the read/write operations, version and base64 encoding. This should be used in paging as well. I think I will create a task for it.

[t2gran]

See issue #5451