Add rental vehicle's fuel percentage and propulsion type to vector tiles API

[leonardehrenfried]

Summary

@alec-georgoff has requested that the properties for fuel percentage and propulsion type be added to the vector tile API.
This PR implements that.

Unit tests

THe current ones where refactored a bit and new ones added.

Changelog

It's sandbox so no.

Bumping the serialization version id

No.

[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.23%. Comparing base (772ae72) to head (213857b).
⚠️ Report is 1 commits behind head on dev-2.x.

Files with missing lines	Patch %	Lines
...mapper/DigitransitRentalVehiclePropertyMapper.java	83.33%	0 Missing and 1 partial ⚠️
.../apis/transmodel/model/stop/RentalVehicleType.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             dev-2.x    #7054      +/-   ##
=============================================
- Coverage      72.23%   72.23%   -0.01%     
+ Complexity     20169    20168       -1     
=============================================
  Files           2188     2188              
  Lines          81186    81188       +2     
  Branches        8141     8142       +1     
=============================================
+ Hits           58645    58646       +1     
+ Misses         19667    19666       -1     
- Partials        2874     2876       +2     

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[binh-dam-ibigroup]

Works with Seattle GBFS