LSP provider capabilities

[al1-ce]

I can't really find anything for first two so I'm sorry if this issue is duplicate

I'm mostly using neovim with builtin LSP and lspsaga/telescope for easier LSP interactions. And after using it for a while I've noticed serve-d is missing couple of nice features, which are mainly are:

• implementationProvider (:Telescope lsp_implementations)
• referenceProvider (:Telescope lsp_references, :Lspsaga lsp_finder)
• rename capability (:Lspsaga rename) (this one is dup of Feature: Variable/Function Renaming #98)
• prepareCallHierarchy (:Lspsaga incomming_calls, :Lspsaga outgoing_calls)

Neovim configuration if needed for some reason with server config
Telescope LSP picker
LspSaga
Nvim LSP