Merge #8131

Merge #8131

8131: Do smart case fuzzy search during flyimports r=SomeoneToIgnore a=SomeoneToIgnore

For now, last actionable part of https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0/topic/autoimport.20weirdness

Should help https://github.com/rust-analyzer/rust-analyzer/issues/7902

Now during the flyimport completion, if the input is searched case-sensitively, if the input contains any non-lowercase letters; otherwise the lookup done as before, case-insensitively.

Co-authored-by: Kirill Bulatov <mail4score@gmail.com>