Add tracking of cabal files

Author: VeryMilkyJoe

src/extension.ts

@@ -264,6 +264,7 @@ async function activateServerForFolder(context: ExtensionContext, uri: Uri, fold
     documentSelector: [
       { scheme: 'file', language: 'haskell', pattern: pat },
       { scheme: 'file', language: 'literate haskell', pattern: pat },
+      { scheme: 'file', language: 'cabal', pattern: pat },
     ],
     synchronize: {
       // Synchronize the setting section 'haskell' to the server.