Redesign the Java hosting integration

[marshalhayes]

Following up from #887, it seems the Java hosting integration could use some updating so it better aligns with the current Aspire design.

I'm creating this discussion to talk about what that should look like, as well as what other improvements can be made.

Here are some thoughts to get the discussion started:

Executable apps

• Add support for Gradle. I personally don't use Gradle much, but it is a popular choice for building Java apps.
• Show build output by default. As a user, I would expect to see the output of my build by default.
• Skip tests when building. I have a lot of tests in some of my apps that often run for several minutes. It would save time to skip them when building locally. Now that I think of it - it might be better to just require the user to specify the build command entirely which would knock out this one and the above.
• Don't require the user to have to specify the path to the application jar. This would be particularly useful when using AddMavenBuild() and when the jar path includes a version like app-1.0.0.jar.

Container apps
I haven't used these yet, so I'll share my thoughts when I do.

[marshalhayes]

@aaronpowell, thanks for merging #888. Would love to hear your thoughts on what improvements could be made to the Java hosting integration.

[aaronpowell]

I'm pretty much the wrong person to provide any real guidance as I haven't done Java in like 20 years, so I have no clue what the current toolchains or anything look like.

My comment about the integration was more that it was one of the very first that was created, so does it still match how we would design a Java integration for Aspire 9.x? Does it make sense to provide the bundled .jar or a pre-built container image, or should it act more like a C# project where you provide an entry point file or folder, and then it calls the appropriate build commands (which is your last point)? How about the SpringApp container version, does that make sense or is it not a needed API when you can just create a container resource?

That sort of stuff is what was on my mind.