We need more incrementality tests

[Veykril]

We currently only have a very few for the defmap here
https://github.com/rust-lang/rust-analyzer/blob/87e2c310f9f1770aa09c1223ae4a5b7b8ce33360/crates/hir-def/src/nameres/tests/incremental.rs
and while def map incrementality is the most important one to get right we should also check for more things, like typechecking not being invalidated in expected cases etc

[Veykril]

Re-opening this, we still lack a lot of tests for this on differeing levels, especially on bodies wrt to macros I'd say, #18264 is an important one for this