Adds a new setting for the gap size between tiles in a layout. Also
updates the resize handle calculations so they are dynamically generated
based on the gap size. Also updates the styling for the resize handles
to be more robust.
This also updates the default gap size to 3px.
This also slims out the Block Frame padding so it is just enough that
the blocks don't overlap when there's no gap.
This makes the background for the "wave-theme-dark" theme transparent.
The light theme is still opaque because otherwise it will look somewhat
dark.
This also suppresses TypeScript/JavaScript import errors in the default
linter, since we don't have support for project directories.
This also reworks the useWidth and useHeight hooks to use the
useResizeObserver hook, which limits the number of ResizeObserver
instances floating around, thereby improving performance
