The Completion request is sent from the client to the server to compute completion items at a given cursor position.
Completion items are presented in the IntelliSense user interface. If computing full completion items is expensive,
servers can additionally provide a handler for the completion item resolve request ('completionItem/resolve').
This request is sent when a completion item is selected in the user interface. A typically use case is for example:
the 'textDocument/completion' request doesn't fill in the documentation property for returned completion items
since it is expensive to compute. When the item is selected in the user interface then a 'completionItem/resolve'
request is sent with the selected completion item as a param. The returned completion item should have the
documentation property filled in.
Formats the value using the given formatter. Read more
METHOD: &'static str = "textDocument/completion"