3397: UI test cleanup: Extract expect_fun_call tests r=matthiaskrgr a=phansch
Note that the new stderr file does not include a `shadow-unrelated`
error, because the new UI test file does not use `#![warn(clippy::all)]`
cc #2038
3398: UI test cleanup: Extract match_overlapping_arm tests r=matthiaskrgr a=phansch
cc #2038
Co-authored-by: Philipp Hansch <dev@phansch.net>