Goto Type Definition should probably use range and not just position

[matklad]

At the moment, goto type definition is specked to use TextDocumentPositionParams:

https://microsoft.github.io/language-server-protocol/specification#textDocument_typeDefinition

I think it is reasonable to use Range, and not just position, for this request. I imagine a user might want to use "extend selection" to select an expression (like foo.bar.baz.foo()), and then "goto type definition" to get to the type of the result.

[dbaeumer]

Dups #1029