fix(richtext-lexical): don't reset link drawer form state during lexical updates

[harsha-cpp]

fixes #15719.

problem: autosave triggers a lexical state update, which calls $updateLinkEditor, which calls setStateData(data) with the node's committed fields. DrawerContent has data in its useEffect dependency array, so every update re-fetches the initial form state — reverting any in-progress edits (e.g. switching link type from custom to internal) back to what's persisted in the lexical node.

fix: expose isOpen from useLexicalDrawer and guard setStateData in $updateLinkEditor. when the drawer is already open, lexical updates no longer overwrite the form's initial state; the drawer only resets when it opens fresh for a new link.