Highlight the "type-to-search" aspect of selecting package versions

[pavithraes]

This functionality already exists, and we can make it more obvious.

In the following video, I'm typing some numbers and the prompt automatically jumps to the matching versions. It'll be nice to make this feature more obvious -- possibly by including a cursor and displaying what the user is typing?

Screen.Recording.2022-10-07.at.6.27.31.PM.mov

Note that this is a minor enhancement, hence a "nice-to-have". :)

[trallard]

From #309

Proposal: allow to add package name and version without scrolling.

Example: I want to add "python". The expectation is that I'll scroll and find it, but there're too many matches. The only way to add it is to go to raw YAML, but it'll erase all your changes if those are not saved. Not practical.

Ideal workflow: I type "python", it shows the selector, but I can still add it (by keeping it as is and moving focus to the version field) and specify its version. When I switch to the version field, it should pull actual "python" versions, what I specified in the first field. The same for version: in case there are too many versions, I should be able to just type it in the new UI, but also be able to select from the list.

Also: when I mistype something, it should be visually clear. For instance, text highlighted in red immediately. Not sure if red is the best color for this. Colors need to be chosen with a11y in mind.