Add `SnapToGrid` methods

[peterstace]

Description

These methods transform the receiver geometry by snapping its control points to a base 10 grid.

Check List

Have you:

• Added unit tests? Yes.

• Add cmprefimpl tests? (if appropriate?) N/A

• Updated release notes? (if appropriate?) Yes.

Related Issue

• Please link to the related issue(s).

[peterstace]

Thanks for reviewing @albertteoh!