LSP: Add hover docs for functions used with the pipe operator

[ameknite]

Example: This works

This doesn't work

[lpil]

Thank you

[Acepie]

Hi, I wanted to try taking a look at fixing this and wrote up https://github.com/gleam-lang/gleam/pull/2678 idk if this is the right way to solve this but it passes a basic repro case at the very least