fix(lane_change): activate turn signal as soon as we have the intention to change lanes

[mkquda]

Description

In the current implementation of LC, the turn signal behaves as follows:

• When approved: activate turn signal when approaching start of lane change
• When waiting for approval: activate turn signal when approaching terminal start

This logic is not intuitive, when it is difficult to find safe LC path due to traffic, turn signal will not be activated until the very end.
We should activate turn signal as soon as we have the intention to do LC, to indicate to other vehicles that we wish to change lanes.

Changes

LC turn signal behavior will be as follows:

When LC path is approved -> activate immediately
When LC path is awaiting approval:

• If no turn signal command from previous module -> activate immediately
• Else -> activate when approaching terminal start

Related links

How was this PR tested?

• PSIM
• TIER IV internal Llink

Notes for reviewers

None.

Interface changes

None.

Effects on system behavior

Turn signal will activate as soon as we have the intention to change lanes, to indicate to other vehicles that we wish to change lanes.

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 40 lines in your changes missing coverage. Please review.

Project coverage is 24.01%. Comparing base (b9b0fa9) to head (f084e76).
Report is 1 commits behind head on main.

Files	Patch %	Lines
...are_behavior_path_lane_change_module/src/scene.cpp	0.00%	22 Missing ⚠️
...avior_path_lane_change_module/utils/base_class.hpp	0.00%	18 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8571      +/-   ##
==========================================
- Coverage   24.06%   24.01%   -0.06%     
==========================================
  Files        1398     1397       -1     
  Lines      102639   102344     -295     
  Branches    39023    38962      -61     
==========================================
- Hits        24704    24580     -124     
+ Misses      75403    75246     -157     
+ Partials     2532     2518      -14     

Flag	Coverage Δ		*Carryforward flag
differential	15.30% <0.00%> (?)
total	24.06% <ø> (-0.01%)	⬇️	Carriedforward from 2234b35

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

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[zulfaqar-azmi-t4]

Looks good

Before:

Turn signal will be turned off once lane change is cancelled, or while lane changing is not approved.

cap-.2024-08-23-13-04-19.mp4

After:

Turn signal remains on.

cap-.2024-08-23-12-03-21.mp4