Add support for park and ride itineraries when calculating CO2 emissions

[sharhio]

Summary

Park and ride journeys taken into account in CO2 emission calculations:

• When itinerary contains both street legs and transit legs and emissions are calculated for transit legs, CO2 emission calculation combines transit journey and car journey emissions.
• When itinerary contains both street legs and transit legs, but emissions are not calculated for transit legs, no CO2 value is returned.

Issue

Park and ride journeys receive results based on the car journey alone.

Unit tests

Tests added in file EmissionsServiceTest.java
Tests for:

• Getting results that combine transitLeg and streetLeg CO2 emissions.
• Not getting results for itineraries with routes that are missing CO2 emission data, but also contain streetLegs.

Manual testing was also performed.

[leonardehrenfried]

Please run the formatter.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (37a8367) 66.85% compared to head (112e9ad) 66.85%.

Additional details and impacted files

@@            Coverage Diff             @@
##             dev-2.x    #5489   +/-   ##
==========================================
  Coverage      66.85%   66.85%           
- Complexity     15650    15655    +5     
==========================================
  Files           1817     1817           
  Lines          70158    70160    +2     
  Branches        7379     7383    +4     
==========================================
+ Hits           46902    46904    +2     
  Misses         20798    20798           
  Partials        2458     2458           

Files	Coverage Δ
...opentripplanner/ext/emissions/EmissionsFilter.java	94.00% <90.00%> (-1.84%)	⬇️

... and 1 file with indirect coverage changes

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[leonardehrenfried]

Please have a look at my comments.

[leonardehrenfried]

Please resolve the conflicts.