[mlir-lsp] Rename OutgoingNotification (NFC) (#90076)

Rename `OutgoingNotification` to `OutgoingMessage`, since the same
callback function type will be used in a future commit to represent
outgoing requests, in addition to outgoing notifications.

mlir/include/mlir/Tools/lsp-server-support/Transport.h

@@ -95,10 +95,10 @@ private:
 template <typename T>
 using Callback = llvm::unique_function<void(llvm::Expected<T>)>;
 
-/// An OutgoingNotification<T> is a function used for outgoing notifications
-/// send to the client.
+/// An OutgoingMessage<T> is a function used for outgoing requests or
+/// notifications to send to the client.
 template <typename T>
-using OutgoingNotification = llvm::unique_function<void(const T &)>;
+using OutgoingMessage = llvm::unique_function<void(const T &)>;
 
 /// A handler used to process the incoming transport messages.
 class MessageHandler {
@@ -160,9 +160,10 @@ public:
     };
   }
 
-  /// Create an OutgoingNotification object used for the given method.
+  /// Create an OutgoingMessage function that, when called, sends a notification
+  /// with the given method via the transport.
   template <typename T>
-  OutgoingNotification<T> outgoingNotification(llvm::StringLiteral method) {
+  OutgoingMessage<T> outgoingNotification(llvm::StringLiteral method) {
     return [&, method](const T &params) {
       std::lock_guard<std::mutex> transportLock(transportOutputMutex);
       Logger::info("--> {0}", method);

mlir/lib/Tools/mlir-lsp-server/LSPServer.cpp

@@ -91,7 +91,7 @@ struct LSPServer {
 
   /// An outgoing notification used to send diagnostics to the client when they
   /// are ready to be processed.
-  OutgoingNotification<PublishDiagnosticsParams> publishDiagnostics;
+  OutgoingMessage<PublishDiagnosticsParams> publishDiagnostics;
 
   /// Used to indicate that the 'shutdown' request was received from the
   /// Language Server client.

mlir/lib/Tools/mlir-pdll-lsp-server/LSPServer.cpp

@@ -104,7 +104,7 @@ struct LSPServer {
 
   /// An outgoing notification used to send diagnostics to the client when they
   /// are ready to be processed.
-  OutgoingNotification<PublishDiagnosticsParams> publishDiagnostics;
+  OutgoingMessage<PublishDiagnosticsParams> publishDiagnostics;
 
   /// Used to indicate that the 'shutdown' request was received from the
   /// Language Server client.

mlir/lib/Tools/tblgen-lsp-server/LSPServer.cpp

@@ -72,7 +72,7 @@ struct LSPServer {
 
   /// An outgoing notification used to send diagnostics to the client when they
   /// are ready to be processed.
-  OutgoingNotification<PublishDiagnosticsParams> publishDiagnostics;
+  OutgoingMessage<PublishDiagnosticsParams> publishDiagnostics;
 
   /// Used to indicate that the 'shutdown' request was received from the
   /// Language Server client.