Fill point_before_trajectory with same information as trajectory

[fmauch]

When executing a trajectory with a start time in the future, the trajectory interpolation will create a setpoint at the robot's current configuration based on the state interface information.

However, when the state interface for example doesn't have acceleration information, but the trajectory does contain position, velocity and acceleration, the segment from the current state to the first trajectory point will not use quintic spline interpolation, though the rest of the trajectory will.

This commit fills the current state with velocity and acceleration information if it is not given in the state interfaces but it is defined in the trajectory's first point.

This fixes #2015

Velocity profile with first point in the future / at other position without this PR applied:

Velocity profile with first point in the future / at other position with this PR applied:

I know that this is strictly speaking behavior changing, but I would nevertheless consider this a bugfix. This could, of course get an opt-in parameter on released versions to avoid the behavior change if desired.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.92%. Comparing base (36cfca8) to head (408fec6).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2043   +/-   ##
=======================================
  Coverage   84.91%   84.92%           
=======================================
  Files         148      148           
  Lines       14367    14403   +36     
  Branches     1230     1232    +2     
=======================================
+ Hits        12200    12232   +32     
- Misses       1740     1742    +2     
- Partials      427      429    +2     

Flag	Coverage Δ
unittests	84.92% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
joint_trajectory_controller/src/trajectory.cpp	89.90% <100.00%> (-1.73%)	⬇️
...int_trajectory_controller/test/test_trajectory.cpp	100.00% <100.00%> (ø)

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[christophfroehlich]

LGTM.

I'm not sure if the ABI checker is right here, do we care? Do you want to backport this?