Do not close/reopen live preview on currentDocumentChange

This PR merges to `randy/live-dev-fixes` for #6889. This is not for `master`.

* Optimization of live preview to the connected inspector and loaded agents instead of closing and reopening the browser
* Use `Page.navigate()` instead and update agent and server state as needed.
* Clean up agents to reset state if necessary on `frameNavigated`
* Add original message data to Inspector protocol error logging to map errors to the originating message (if it exists)
* Update "live development" strings to "live preview"