feat: add the lanelet length test

[HansOersted]

Description

Add the lanelet length test.

Tests performed

Not applicable.

Effects on system behavior

Not applicable.

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[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 16.31%. Comparing base (a32312e) to head (4702693).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...are_lanelet2_extension/test/src/test_utilities.cpp	66.66%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #39      +/-   ##
==========================================
+ Coverage   16.08%   16.31%   +0.22%     
==========================================
  Files          42       42              
  Lines        3083     3089       +6     
  Branches     1395     1397       +2     
==========================================
+ Hits          496      504       +8     
+ Misses       2494     2490       -4     
- Partials       93       95       +2     

Flag	Coverage Δ		*Carryforward flag
differential	16.31% <66.66%> (-0.44%)	⬇️
total	16.08% <ø> (ø)		Carriedforward from b46c66e

*This pull request uses carry forward flags. Click here to find out more.

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