Refactor permission check for canned query

[simonw]

This code here (TODO is follow-on from #808).

datasette/datasette/views/database.py

Lines 133 to 142 in 86dec9e

	# Respect canned query permissions
	if canned_query:
	await self.check_permission(
	request, "view-query", "query", (database, canned_query)
	)
	# TODO: fix this to use that permission check
	if not actor_matches_allow(
	request.scope.get("actor", None), metadata.get("allow")
	):
	return Response("Permission denied", status=403)

I can improve this with extra code in https://github.com/simonw/datasette/blob/86dec9e8fffd6c4efec928ae9b5713748dec7e74/datasette/default_permissions.py

[simonw]

This is obsoleted by #811.