fix(ui): canvas filter and SAM module fixes

[psychedelicious]

Summary

• When filtering, we used the parent entity's buffer renderer to render the filter preview. An sloppy copy-paste resulted in the filter committing the buffer when it should have been cleared when saving-as. This fixes the only cause I can imagine for this issue reported by @skunkworxdark.
• But akshually, there's no need to use the buffer renderer at all. The canvas SAM module renders its canvas objects directly to the parent layer, without using the parent's object renderers. This better separates the logic. Updated the filter module to use this pattern instead.
• Update the filter module with the more resilient and clearer logic from the SAM module. Namely, using a hash to determine if we've already processed the given points, and explicit methods to reset the module's ephemeral state and do a teardown once we finish filtering.
  • These two modules are very similar. It makes sense to share the same overall logic between them, but there are enough differences that they can't share a class or inherit from each other.
• Update the filter and select object UIs to handle an edge case where you reset them, but they don't auto-process.
• Use node "adoption" to prevent the original layer from briefly appearing while applying a filter or segment operation.
• Update the comments in the filter module to match the documentation quality of the SAM module.

Related Issues / Discussions

this issue reported by @skunkworxdark

QA Instructions

Try out filtering and segmenting, just kinda fuzz-test it.

I don't know how to reliably repro @skunkworxdark's issue but it there should be no way it can happen now, because a filtered image is now never rendered outside the safe confines of the filter module.

Merge Plan

n/a

Checklist

• The PR has a short but descriptive title, suitable for a changelog