refactor(appkit): retire toPluginWithInstance; consolidate on fromPlugin + fix schema/routing bugs#300

MarioCadenas wants to merge 5 commits intoagent/5g-retire-deprecated-agentdatabricks/appkit:agent/5g-retire-deprecated-agentfrom

agent/5h-retire-toplugininstancedatabricks/appkit:agent/5h-retire-toplugininstanceCopy head branch name to clipboard