Add typescript-eslint-language-service (#30015)

webapp/channels/webpack.config.js

@@ -18,10 +18,14 @@ const packageJson = require('./package.json');
 
 const NPM_TARGET = process.env.npm_lifecycle_event;
 
+// list of known code editors that set an environment variable.
+const knownCodeEditors = ['VSCODE_CWD', 'INSIDE_EMACS'];
+const isInsideCodeEditor = knownCodeEditors.some((editor) => process.env[editor]);
+
 const targetIsRun = NPM_TARGET?.startsWith('run');
 const targetIsStats = NPM_TARGET === 'stats';
 const targetIsDevServer = NPM_TARGET?.startsWith('dev-server');
-const targetIsEslint = NPM_TARGET?.startsWith('check') || NPM_TARGET === 'fix' || process.env.VSCODE_CWD;
+const targetIsEslint = NPM_TARGET?.startsWith('check') || NPM_TARGET === 'fix' || isInsideCodeEditor;
 
 const DEV = targetIsRun || targetIsStats || targetIsDevServer;