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>
Curiously, LSP uses different enums for those, and unsurprising and
annoyingly, there are things which exist in one but not in the other.
Let's not repeat the mistake and unify the two things
