Fix many 'file change detected' messages

Fixes NativeScript/nativescript-cli#3687

When `tns run android` command is executed, a typescript watcher is started. When project is prepared {N} CLI moves all files in platforms directory. This triggers a typescript watcher to print `File change detected. Starting incremental compilation...` message many times. This PR hides all messages from typescript compiler except errors. So the user will see only typescript errors. Actually when the command is executed with --log trace option, all messages from typescript compiler will be printed.

Author: Fatme

lib/compiler.js

@@ -64,9 +64,27 @@ function runTypeScriptCompiler(logger, projectDir, options) {
 			var stringData = data.toString();
 			// Prevent console clear. Fixed the behaviour for typescript 2.7.1 and 2.7.2. Should be deleted after dropping support for 2.7.x version.
 			// https://github.com/Microsoft/TypeScript/blob/master/src/compiler/sys.ts#L623
-			if (stringData !== "\x1Bc") {
-				logger.info(stringData);
+			let filteredData = stringData
+				.split("\n")
+				.map(row => row.replace("\x1Bc", ""))
+				.filter(r => !!r)
+				.join("\n");
+
+			if (filteredData) {
+				const logLevel = logger.getLevel();
+				const isTraceLogLevel = logLevel && /trace/i.test(logLevel);
+
+				if (isTraceLogLevel) {
+					nodeArgs.push("--listEmittedFiles");
+					logger.trace(filteredData);
+				}
+				
+				// https://github.com/Microsoft/TypeScript/blob/e53e56cf8212e45d0ebdd6affe462d161c7e0dc5/src/compiler/watch.ts#L160
+				if (!isTraceLogLevel && filteredData.indexOf("error") !== -1) {
+					logger.info(filteredData);
+				}
 			}
+
 			if (options.watch && stringData.toLowerCase().indexOf("watching for file changes.") !== -1 && !isResolved) {
 				isResolved = true;
 				resolve();