Support adding missing imports

[bsutton]

Currently it doesn't seem to find missing imports.

It would be great it could find and add missing imports.

If there is any ambiguity then it should display a list of alternatives and let user choose the appropriate one.

The dialog should have a 'skip' button if I'm uncertain which one to choose. This allows my to disambiguate other imports and come back to any that I need to resolve.

It would be really nice if over time it changed the sort order for the above selection dialog based on the most commonly selected import.

[luanpotter]

Thanks for the suggestions, @bsutton :)

It would be, but this seems a bit more complex to implement, having to meddle with dart and flutter's APIs, probably. I'd need to do some studying before trying such a feat.

If you'd like to contribute, please be m guest to help out with a PR :)