fix: stop handling SIGINT signal

When Ctrl+C is used in terminal, CLI receives SIGINT signal and tries to clear its resources. In Node.js, when you handle SIGINT signal, you'll have to clean all resources on your own. This leads to different problems, for example in case you press Ctrl+C during doctor execution, CLI will only kill the doctor process, but will continue working.
Instead of handling the SIGINT signal, let the OS handle it on its own. This works quite well except one thing - any package that is required may add handler for SIGINT signal and this will break the idea. So repace the `process.on` function with our own one which does not allow adding handler for SIGINT signal.

Author: rosen-vladimirov

lib/common/services/process-service.ts

@@ -1,5 +1,5 @@
 export class ProcessService implements IProcessService {
-	private static PROCESS_EXIT_SIGNALS = ["exit", "SIGINT", "SIGTERM"];
+	private static PROCESS_EXIT_SIGNALS = ["exit", "SIGTERM"];
 	private _listeners: IListener[];
 
 	public get listenersCount(): number {

lib/common/test/unit-tests/process-service.ts

@@ -2,7 +2,7 @@ import { Yok } from "../../yok";
 import { ProcessService } from "../../services/process-service";
 import { assert } from "chai";
 
-const processExitSignals = ["exit", "SIGINT", "SIGTERM"];
+const processExitSignals = ["exit", "SIGTERM"];
 const emptyFunction = () => { /* no implementation required */ };
 function createTestInjector(): IInjector {
 	const testInjector = new Yok();

lib/nativescript-cli.ts

@@ -1,21 +1,30 @@
 require("./bootstrap");
+
 import { EOL } from "os";
 import * as shelljs from "shelljs";
 shelljs.config.silent = true;
 shelljs.config.fatal = true;
 import { installUncaughtExceptionListener } from "./common/errors";
+import { settlePromises } from "./common/helpers";
 installUncaughtExceptionListener(process.exit.bind(process, ErrorCodes.UNCAUGHT));
 
-import { settlePromises } from "./common/helpers";
+const logger: ILogger = $injector.resolve("logger");
+const originalProcessOn = process.on;
+
+process.on = (event: string, listener: any): any => {
+	if (event === "SIGINT") {
+		logger.trace(new Error(`Trying to handle SIGINT event. CLI overrides this behavior and does not allow handling SIGINT as this causes issues with Ctrl + C in terminal`).stack);
+	} else {
+		return originalProcessOn.apply(process, [event, listener]);
+	}
+};
 
 /* tslint:disable:no-floating-promises */
 (async () => {
 	const config: Config.IConfig = $injector.resolve("$config");
 	const err: IErrors = $injector.resolve("$errors");
 	err.printCallStack = config.DEBUG;
 
-	const logger: ILogger = $injector.resolve("logger");
-
 	const extensibilityService: IExtensibilityService = $injector.resolve("extensibilityService");
 	try {
 		await settlePromises<IExtensionData>(extensibilityService.loadExtensions());