Allow users to edit what they've typed after "creating" an option in the creatable select

[madelson]

Today, creatable selects allow you to type freely and edit what you've typed just like in a regular textbox. HOWEVER, once you actually select 'Create "XYZ"', it won't let you edit the typed selection. You can still type, but this starts you over from scratch. It would be nice if the textbox continued to be editable post-selection, acting just as it did before you selected. I think #4646 might be asking for the same thing, but it is unclear.