macOS: add native find and all its friends

[peteschaffner]

Coming from Apple Terminal and iTerm2, I miss the ability to find in the terminal. iTerm2's implementation is all custom (from what I remember), but I think we could possibly lean hard into NSTextFinder and get pretty far in terms of the actual search bar UI. I'm guessing the communication with the terminal might be tricking though.

CleanShot.2024-01-30.at.10.19.13.mp4

[mitchellh]

I agree! Linking this to #189. That issue is about implementing scrollback search in general but I think this belongs there since UI about search will also be an issue. Thank you!