Improve intellisense completions with complex qualifiers

[darzu]

Fixes: https://github.com/microsoft/pxt-arcade/issues/2547

Before:

After:

It's not a perfect solution, but it's better than what was.

My previous attempt at this (dazuniga/a_button_snippet branch) involved tracking and passing qualifiers from the snippet generation process, but it had some drawbacks and this achieves basically the same thing.

[pelikhan]

Outdated?

[darzu]

Might still be needed for .py work