Allow request ids to be strings (#1929)

The LSP spec allows this: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#requestMessage

Addons that want to sent requests must provide an id but since the
counter is internal to the server that is not easily possible at the moment.

See the conversation starting at Shopify/ruby-lsp-rails#326 (comment) for more context

lib/ruby_lsp/utils.rb

@@ -75,7 +75,7 @@ def to_hash
   class Request < Message
     extend T::Sig
 
-    sig { params(id: Integer, method: String, params: Object).void }
+    sig { params(id: T.any(Integer, String), method: String, params: Object).void }
     def initialize(id:, method:, params:)
       @id = id
       super(method: method, params: params)