Fix code review actions in PR #32053
Fix code review actions in PR #32053

Split `fileline_note` into a `file_line note` and `span_suggestion` as per
@Manishearth's suggestions.

Change nested `match`es to `if let`s.

graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,graydon/rust,aidancully/rust,GBGamer/rust,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,aidancully/rust