Use 'update-notifier' for new version notice

[WesCossick]

See https://www.npmjs.com/package/update-notifier. This is probably better and easier to maintain than our own method.

[WesCossick]

Here's the old code, which was found in actions/init.ts:

// Handle new version warning
if (settings.newVersionWarning.enabled && settings.app.packageName) {
	// Determine where to store the version
	const pathToLatestVersion = path.join(
		__dirname,
		`../app-versions/${settings.app.packageName.replace(/[^a-zA-Z0-9-.]/g, '=')}`
	);

	// Make the directory
	const appVersionsDirectory = path.dirname(pathToLatestVersion);

	if (!fs.existsSync(appVersionsDirectory)) {
		fs.mkdirSync(appVersionsDirectory);
		await verboseLog(`Created directory: ${appVersionsDirectory}`);
	}

	// Warning message
	if (fs.existsSync(pathToLatestVersion)) {
		// Get values
		const latestVersion = semver.clean(`${fs.readFileSync(pathToLatestVersion)}`);
		const currentVersion = semver.clean(settings.app.version || '');

		// Only continue if we have both
		if (latestVersion && currentVersion) {
			const bothVersionsAreValid = semver.valid(latestVersion) && semver.valid(currentVersion);

			// Verbose output
			await verboseLog(`Previously retrieved latest app version: ${latestVersion}`);
			await verboseLog(`Cleaned-up current app version: ${currentVersion}`);
			await verboseLog(`Both versions are valid: ${bothVersionsAreValid ? 'yes' : 'no'}`);

			// Determine if warning is needed
			if (bothVersionsAreValid && semver.gt(latestVersion, currentVersion)) {
				console.log(
					chalk.yellow(
						`You're using an outdated version of ${
							settings.app.name
						} (${currentVersion}). The latest version is ${chalk.bold(latestVersion)}`
					)
				);
				console.log(
					`${chalk.yellow(
						`  > Upgrade by running: ${chalk.bold(
							`npm install ${settings.newVersionWarning.installedGlobally ? '--global ' : ''}${
								settings.app.packageName
							}@${latestVersion}`
						)}`
					)}\n`
				);
			}
		}
	}

	// Check asynchronously if there's a new published version
	const versionCheck = spawn('npm', ['view', settings.app.packageName, 'version']);

	versionCheck.stdout.on('data', (stdout: string) => {
		fs.writeFile(pathToLatestVersion, semver.clean(`${stdout}`) ?? '', 'utf8', () => {
			// Do nothing
		});
	});
}