Support React Element as optionText in AutocompleteInput

[yelworc]

Is your feature request related to a problem? Please describe.
I'd like to apply some simple custom formatting to the choices displayed in an AutocompleteInput (so the available values are presented the same way as in other places, e.g. in a list view).

Describe the solution you'd like
Other input elements (e.g. SelectInput) allow passing a React Element as the optionText prop, which enables flexible customization of the way the values are rendered. AutocompleteInput only accepts a string (choice field name) or a function returning a string in that prop.

Additional context
I'm guessing it currently only works with plain strings is because there is already some formatting applied to the autocompleted choices (highlighting of the matching substring). A custom element passed as optionText would have to implement that itself, if desired.

I checked the reimplemented AutocompleteInput in the latest v3 branch, but this particular aspect seems to be unchanged so far.

[fzaninotto]

Fixed by #3683