Merge #7353

Merge #7353

7353: Add LifetimeParam and ConstParam to CompletionItemKind r=matklad a=Veykril

Adds `LifetimeParam` and `ConstParam` to `CompletionItemKind` and maps them both to `TypeParam` in the protocol conversion as there are no equivalents, so nothing really changes there.
`ConstParam` could be mapped to `Const` I guess but I'm split on whether that would be better?

Additions were solely inspired by (the single) test output for const params.

Also sorts the variants of `CompletionItemKind` and its to_proto match.

Co-authored-by: Lukas Wirth <lukastw97@gmail.com>