More efficient name completion data retrieval

[Rexios80]

I'm thinking we have two options:

Store the package names in the Realtime Database during backend updates

Has the added benefit of only showing packages we have data for

Use the new optimized name completion endpoint

https://pub.dev/help/api#additional-apis
https://pub.dev/api/package-name-completion-data

Would need to PR pub_api_client to add this
Will not contain all packages we have data for (especially an issue if we use the suggestions to do things like adding to comparison)

[Rexios80]

Another thought is we could use the optimized name completion endpoint and just show the current query as the first option

[Rexios80]

That's what I ended up doing