Guide user to install JDK if no JDK is found #1066

This is to adjust the UX to better support the embedded JRE in JLS.

The upstream JLS is planning to embed a JRE to launch the Java tooling itself. It is used to address the famous getting started issue about the minimum requirements for JDK 11. Since the embedded JRE is a pruned JRE with only a limited number of Java modules, it is not recommended for launching the user's Java application, and it is the user's responsibility to install the JDK to launch their application.

The debugger should add logic to check if the target machine has the JDK installed before launching the user's Java application, and prompt them to install it if necessary.