Update buildall and doc to generate bloop projects for test debugging

[gerashegalov]

• Require JDK11+ in doc and buildall for creating bloop projects
• make sure all sub-modules are included
• figure out why product classes when debugging a tests class are shown "unknown source" while Spark dependencies retrieved with -DdownloadSources are fine.

h/t: originally reported by @PhilDakin

Originally posted by @gerashegalov in #9542 (comment)

[PhilDakin]

@gerashegalov depending on expected turnaround time, I'd be keen to take this on as a first contribution.

At the latest I would open a PR by 11/2.

[gerashegalov]

Thank you @PhilDakin, go for it!

[gerashegalov]

related to #9556

[PhilDakin]

buildall/doc changes are easy. Still looking into the "Unknown Sources" issue. See corresponding issue on the Metals project: scalameta/metals#5807

[gerashegalov]

buildall/doc changes are easy. Still looking into the "Unknown Sources" issue. See corresponding issue on the Metals project: scalameta/metals#5807

Thanks for bringing up the issue with the scalameta team. We can handle this in issues and PRs separate from "simple" changes to the build and documentation.

[gerashegalov]

This is fixed by #9615,

"Unknown source" is filed scalameta/metals#5807