Support generating dockerfile for Java App

[kyliel]

1. Generate a dockerfile for Java App. Now Go, .NET, Nodejs are supported.
2. Optimize dockerfile for typical Java App (e.g. Tomcat and/or Spring is used).

[kyliel]

@andxu from Java tooling team will work on it.

[StephenWeatherford]

@kyliel This was implemented a while ago. Please give it a spin. Thanks.

[kyliel]

Yes, confirmed. This was implemented. I love this feature. Thank you.

[StephenWeatherford]

Great to hear, thanks.