Update autocomplete to enable cache and return most recent requests

[vwbusguy]

This adds two things to the AutoComplete instantiations:

• cache - this is a minimal benefit, but still means less db queries if someone uses backspace and re-types something
• adds a simple query counter so that older query results from slower database transactions don't overwrite newer ones

Fixes #766

Tested this in my local Nextcloud (29.0.4) with dev tools in Firefox 128.0.

[matiasdelellis]

Hi @vwbusguy
Tomorrow I hope to be able to do a review. 😬

[vwbusguy]

Hi @vwbusguy
Tomorrow I hope to be able to do a review. 😬

For what it's worth, I'll be at the Nextcloud Community/Contributors conference in Berlin in about a week. If you'll be there, I'm happy to review this with you there.