rls no longer builds after rust-lang/rust#58140

[rust-highfive]

Hello, this is your friendly neighborhood mergebot.
After merging PR #58140, I observed that the tool rls no longer builds.
A follow-up PR to the repository https://github.com/rust-lang/rls is needed to fix the fallout.

cc @eddyb, do you think you would have time to do the follow-up work?
If so, that would be great!

cc @nikomatsakis, the PR reviewer, and @rust-lang/compiler -- nominating for prioritization.

[kennytm]

Error is caused by clippy-lints dependency.

[01:26:39] error[E0433]: failed to resolve: could not find `item_path` in `ty`
[01:26:39]    --> src/tools/clippy/clippy_lints/src/utils/mod.rs:104:10
[01:26:39]     |
[01:26:39] 104 | impl ty::item_path::ItemPathBuffer for AbsolutePathBuffer {
[01:26:39]     |          ^^^^^^^^^ could not find `item_path` in `ty`
[01:26:39] 
[01:26:39] error[E0433]: failed to resolve: could not find `item_path` in `ty`
[01:26:39]    --> src/tools/clippy/clippy_lints/src/utils/mod.rs:105:33
[01:26:39]     |
[01:26:39] 105 |     fn root_mode(&self) -> &ty::item_path::RootMode {
[01:26:39]     |                                 ^^^^^^^^^ could not find `item_path` in `ty`
[01:26:39] 
[01:26:39] error[E0433]: failed to resolve: could not find `item_path` in `ty`
[01:26:39]    --> src/tools/clippy/clippy_lints/src/utils/mod.rs:106:30
[01:26:39]     |
[01:26:39] 106 |         const ABSOLUTE: &ty::item_path::RootMode = &ty::item_path::RootMode::Absolute;
[01:26:39]     |                              ^^^^^^^^^ could not find `item_path` in `ty`
[01:26:39] 
[01:26:39] error[E0433]: failed to resolve: could not find `item_path` in `ty`
[01:26:39]    --> src/tools/clippy/clippy_lints/src/utils/mod.rs:106:57
[01:26:39]     |
[01:26:39] 106 |         const ABSOLUTE: &ty::item_path::RootMode = &ty::item_path::RootMode::Absolute;
[01:26:39]     |                                                         ^^^^^^^^^ could not find `item_path` in `ty`
[01:26:39] 
[01:26:40] error: aborting due to 4 previous errors

[mati865]

I'm on it.

[eddyb]

@mati865 I would like to review the resulting PR, if you don't mind. You can also PM me (on IRC/Discord) if you have any questions.