Add TriggerReindexRequest to buildinRequests

`TriggerReindexRequest` was missing from the list of builtinRequests,
which caused the LSP to respond with a methodNotFound error when it
recieved a `workspace/triggerReindex` request.

Author: plemarquand

Sources/LanguageServerProtocol/Messages.swift

@@ -69,6 +69,7 @@ public let builtinRequests: [_RequestType.Type] = [
   ShutdownRequest.self,
   SignatureHelpRequest.self,
   SymbolInfoRequest.self,
+  TriggerReindexRequest.self,
   TypeDefinitionRequest.self,
   TypeHierarchyPrepareRequest.self,
   TypeHierarchySubtypesRequest.self,