fix(webpack): don't ignore compilation errors (#9369)

* fix(webpack): Fail build in case of compilation errors.

WebPack's own documentation states that the `err` object **will not**
include compilation errors.

https://webpack.js.org/api/node/#webpack

This fix addresses compilation errors by setting the correct `process.exitCode`
looking at the result of the `stats.hasErrors()` call.

* fix(tsc): Ensure that TypeScript compilation errors are handled.

The `async` flag of the `fork-ts-checker-webpack-plugin` will (by default
in development mode) avoid reporting any errors detected by `tsc` back
to webpack:

https://github.com/TypeStrong/fork-ts-checker-webpack-plugin#options

> If `true` reports issues **after** webpack's compilation is done.
> Thanks to that it doesn't block the compilation.

The problem in this case is that any compilation error will be then
undetectable by the `WatchStatePlugin` which will happily tell the
NativeScript CLI to continue with the build process.

* fix(cli): Do not send the `compilation` message to the CLI on errors.

When the compilation fails, this patch will prevent for the `compilation`
message to be sent back to the CLI, preventing broken builds hitting the device.

packages/webpack5/src/configuration/base.ts

@@ -233,6 +233,11 @@ export default function (config: Config, env: IWebpackEnv = _env): Config {
 			.plugin('ForkTsCheckerWebpackPlugin')
 			.use(ForkTsCheckerWebpackPlugin, [
 				{
+					// If we use "async" errors compiling typescript will be ignored by
+					// WebPack (we will send the "compilation" message back to the CLI,
+					// and the process exit code will be zero), therefore we will end
+					// up with a broken build
+					async: false,
 					typescript: {
 						memoryLimit: 4096,
 					},