#4302 dropdown autofill autocomplete

[staysgt]

Changes

When typing in an autocomplete dropdown menu, pressing 'enter' will autofill the top most/selected user.

Notes

I looked into creating an abstracted component for autcompletes with multiple, but they all followed different patterns/had different UIs implemented. Still happy to implement that if you think its better than adding the autohighlight everywhere

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Closes #4302