Migrate graphql playground to graphiQL

[dctalbot]

What problem would you like to solve? Please describe:
GraphQL playground is being retired in favor of graphiQL

Describe the solution you'd like:
Replace graphql Playground with graphiQL.

Additional context:

• We should also implement an SRI check on the resource, a security mechanism that is missing today.
• It's also possible to bundle the dependency client-side now that we are running everything in one container, but IMO we should only do so if we can split it into its own chunk so it doesn't bloat the main UI.
• This would be a big change for existing users, so maybe some communication is needed there.

[mastercactapus]

I think long-term we should build it in as a separate bundle that is within GoAlert, but maybe that step would be better after esbuild -- the UI build already takes too long.

In the interim I think a small PR with the SRI attributes with today's code would be good, and then apply the same with the change to graphiQL. Whenever esbuild or whatever build-speed solution we land on gets in, we'll maybe add this to it.

As for the change to users, I think we're safe as long as:

• The URL (/api/graphql/explore) remains the same
• The current user session/auth & endpoint to the current server remains the same
• There's an editing pane and schema docs available in an obvious way