core: add a class to concatenate envelope without deep copy

[eckter]

Fix #6177

1. EnvelopeStopWrapper can use an abstract EnvelopeTimeInterpolate as input
2. rename EnvelopeStopWrapper.iterateCurve to iteratePoints and move it to the interface EnvelopeTimeInterpolate
3. add EnvelopeConcat, implementing EnvelopeTimeInterpolate using a list of envelopes

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (ea45fc5) 26.62% compared to head (181b557) 26.65%.

Files	Patch %	Lines
...ain/java/fr/sncf/osrd/envelope/EnvelopeConcat.java	86.53%	2 Missing and 5 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                dev    #6179      +/-   ##
============================================
+ Coverage     26.62%   26.65%   +0.02%     
- Complexity     2121     2139      +18     
============================================
  Files           929      931       +2     
  Lines        123373   123429      +56     
  Branches       2677     2682       +5     
============================================
+ Hits          32852    32900      +48     
- Misses        88928    88931       +3     
- Partials       1593     1598       +5     

Flag	Coverage Δ
core	78.87% <91.02%> (+0.04%)	⬆️
editoast	74.94% <ø> (-0.01%)	⬇️
front	9.36% <ø> (ø)
gateway	2.55% <ø> (ø)

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[Erashin]

LGTM