fix: start webpack in non watch mode for release builds with snapshot

[Fatme]

When tns run android --release --env.snapshot command is executed, { skipWatcher: true } option is provided. On the other side watch option has default true value so as a result we have { skipWatcher: true and watch: true }. So a release run is started in watch mode. As the watch option is true, NativeScript CLI starts webpack in watch mode. This led to the problem that webpack reports emitted files before the snapshot generation is completed. (note: there is an another issue inside nativescript-dev-webpack plugin itself about the way how emitted files are reported - it should be fixed there.)
As a result, an async issue arise between snapshot generation and gradle build and the following error is thrown:

Warning: The static binding generator will generate extend from:vendor.js implementation
Exception in thread "main" java.io.IOException: File already exists. This may lead to undesired behavior.
Please change the name of one of the extended classes.
File: ./platforms/android/app/src/main/java/com/tns/FragmentClass.java Class: com.tns.FragmentClass
        at org.nativescript.staticbindinggenerator.Generator.writeBindings(Generator.java:112)
        at org.nativescript.staticbindinggenerator.Main.main(Main.java:48)

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What is the current behavior?

What is the new behavior?

Fixes/Implements/Closes #[Issue Number].