Task: Drop use:resize directive in favor of new ResizeObserver bindings

[emmbm]

Task Description

Up until now, svelte didn't offer a binding for observing non-window element resize. With the nowadays broader compat of ResizeObserver, bindings filling that role were recently added.

We have been using our own tiny directive that allows us to listen to resize events. In some cases, this might not be useful anymore.

Actions

• Replace custom directive with newly available bindings where applicable