fix: Fix `ast::Path::segments` implementation calling `ast::Path::segments` on a qualifier currently returns all the segments of the top path instead of just the segments of the qualifier. The issue can be summarized by the simple failing test below: ```rust #[test] fn path_segments() { //use ra_ap_syntax::ast; let path: ast::Path = ...; // e.g. `ast::Path` for "foo::bar::item". let path_segments: Vec<_> = path.segments().collect(); let qualifier_segments: Vec<_> = path.qualifier().unwrap().segments().collect(); assert_eq!(path_segments.len(), qualifier_segments.len() + 1); // Fails because `LHS = RHS`. } ``` This PR: - Fixes the implementation of `ast::Path::segments` - Fixes `ast::Path::segments` callers that either implicitly relied on behavior of previous implementation or exhibited other "wrong" behavior directly related to the result of `ast::Path::segments` (all callers have been reviewed, only one required modification) - Removes unnecessary (and now unused) `ast::Path::segments` alternatives