generator_interior: Count match pattern bindings as borrowed for the whole guard expression
The test case `yielding-in-match-guard.rs` was failing with `-Zdrop-tracking` enabled. The reason is that the copy of a local (`y`) was not counted as a borrow in typeck, while MIR did consider this as borrowed.
The correct thing to do here is to count pattern bindings are borrowed for the whole guard. Instead, what we were doing is to record the type at the use site of the variable and check if the variable comes from a borrowed pattern. Due to the fix for #57017, we were considering too small of a scope for this variable, which meant it was not counted as borrowed.
Because we now unconditionally record the borrow, rather than only for bindings that are used, this PR is also able to remove a lot of the logic around match bindings that was there before.
r? `@nikomatsakis`
f24ef2e296