Problem:
Our LSP type system didnt have a concept of RegistrationMethods, this is where the method to dynamically register for a capability is sent to a different method endpoint then is used to call it. Eg `textDocument/semanticTokens` rather than the specific full/range/delta methods
Solution:
Extended generator to create `vim.lsp.protocol.Methods.Registration` with these registration methods. Also extend `_request_name_to_client_capability` to cover these methods. Adjust typing to suit
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