Add a sketch mirror tool

[franknoirot]

Warning

After discussion about our approach for representing constraints and profiles, we have determined that this feature cannot be included in our V1 project for the following reasons: our KCL mirror function flips profiles' directionality, making them unusable to continue a sketch profile; our function approach does not allow for referencing of mirrored segments or points, nor deleting them. We will prioritize features we can complete in a timely manner for now, but feedback is welcome.

A sketch mirror tool takes a selection of one or more points and segments and an axis line, and creates copies of the elements across the axis.

Existing CAD implementations

• NX's curve mirroring has confused users in the past (v7.5) because it requires a setting to be turned on if the user wants the original curve to "drive" edits to the mirrored curve
• Onshape has this two-way driving relationship by default which feels much more intuitive, because it applies a mirror constraint between the segments and points.

Systemic notes

We need some sort of constraint solving approach in order to support traditional mirroring user expectations.

Engine notes

None

API/KCL notes

1. Ready with a mirror2D standard library function
2. This function has some limitations that do not support traditional workflows:
3. No way to reference mirrored points and segments
4. Segment directionality of mirrored segments is also flipped, so user cannot create completed profiles unless the mirrored halves are touching

Point-and-click notes

1. More restricted approach: show a little icon beside a sketch as “reference geometry”, and a little symbol beside the mirror
2. Less restricted approach: We allow user to select lines / geometry, and hit a mirror button, which mirrors the KCL values using math on client side
3. Might be able to provide a bootleg approach if needed, which creates entirely new segments and drives their angles and length based on the parent segments' parameters and tags. However, reversing the directionality of the curves would be non-trivial.