[DONT MERGE] Test min capture

[arora-aman]

New capture analysis for RFC 2229.

• This PR is to just test the entire bors try suite passes if the feature was to be enabled by default.
• Know issue: let _ = <Place> statements aren't handled properly in closures yet.
• Modified some ui tests to bypass the issue mentioned above.
• Regions for captures maybe created in a different order than before, so updated ui tests to reflect that as well.

r? @ghost