component: Replace linkme with inventory (#30705)

This PR replaces the use of `linkme` with `inventory` for the component
preview registration.

Release Notes:

- N/A

crates/git_ui/Cargo.toml

@@ -35,7 +35,6 @@ itertools.workspace = true
 language.workspace = true
 language_model.workspace = true
 linkify.workspace = true
-linkme.workspace = true
 log.workspace = true
 markdown.workspace = true
 menu.workspace = true