Add "seam carving" as a resize method

@AlexVictoor just published a resizing demo that uses Seam Carving implemented in AssemblyScript: https://alexvictoor.github.io/seam-carving-as/

It seems like it should be quite easy to integrate and would make a great addition to Squoosh as an extra resizing method.

Start with the linked AssemblyScript seam-carving demo, then locate Squoosh's existing resize-method entry point. Confirm how a new method is integrated and what browser behavior it must support; done means seam carving is available as an additional resize option without disrupting existing methods.

Written by the indexing model from the issue text.