Code actions for simplifying common patterns

[nabeelvalley]

This feels like something that might not have a specific end point, but I think it would be really handy for the LSP to spot common patterns that can be simplified, for example converting list.map(thing) |> list.flatten to list.flat_map(thing)

I'm sure there are other possibilities but in general this is the idea

I think it's nice from a productivity standpoint but also helps new developers discover functionality in the standard library