Add tangentToEnd stdlib function

[jtran]

Resolves #4403.

We add a function that gets the angle that's tangent to the end of a given segment. This is useful for making a sketch with an arc followed by a line that smoothly follows the arc.

// Horizontal pill.
pillSketch = startSketchOn('XZ')
  |> startProfileAt([0, 0], %)
  |> line([20, 0], %)
  |> tangentialArcToRelative([0, 10], %, $arc1)
  |> angledLine({
    angle: tangentToEnd(arc1),
    length: 20,
  }, %)
  |> tangentialArcToRelative([0, -10], %)
  |> close(%)

pillExtrude = extrude(10, pillSketch)

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Codecov Report

Attention: Patch coverage is 95.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 86.00%. Comparing base (79dc537) to head (49e9a02).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/wasm-lib/kcl/src/std/segment.rs	87.09%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4541      +/-   ##
==========================================
+ Coverage   85.96%   86.00%   +0.03%     
==========================================
  Files          81       81              
  Lines       29506    29551      +45     
==========================================
+ Hits        25366    25416      +50     
+ Misses       4140     4135       -5     

Flag	Coverage Δ
wasm-lib	86.00% <95.00%> (+0.03%)	⬆️

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[franknoirot]

There is just one case that this doesn't seem to work for me that we should support I think, since we're going the angle utility route: arcTo doesn't return an accurate result:

sketch001 = startSketchOn("XY")
  |> startProfileAt([0, 0], %)
  |> line([5, 0], %)
  |> tangentialArcToRelative([3.14, 2.14], %, $a)
  |> angledLine([segmentTangentialAngle(a), 5], %)
  |> line([-5, 0], %, $b)
  |> angledLine([segmentTangentialAngle(b), 4.07], %)
  |> arcTo({
    end: [10, 10],
    interior: [5.14, 9.14],
  }, %, $c)
  |> angledLine([segmentTangentialAngle(c), 5], %)

It might be worth documenting that:

1. For straight segments, there is no difference between segAng and segmentTangentialAngle
2. For tangential arcs, this is getting the tangency angle coming out of the end of the arc. Maybe that's fine to be implicit because the tangency going in would be a previous segment. But in the future with arcTo I could see a use for getting the tangent angle going into the arc.

[franknoirot]

Nice! Just verified I get the expected behavior in local development. Really cool LFG

[adamchalmers]

Awesome