Allow delaying/disabling the priming build

[anthonyvdotbe]

The extension aggressively does a priming build of each Java project it finds. Often I just want to open workspaces / projects to open a few Java files where basic features suffice, or to work on non-Java projects in the same workspace. The Red Hat extension solves this with a lightweight mode (see java.server.launchMode). An alternative would be to make it configurable on the user/workspace/folder level to decide whether a priming build must be done or not, and add a command to do a priming build on demand for a given project or set of projects.

[anthonyvdotbe]

Even worse: apparently it does these priming builds on every startup. Possibly it only does the ones that failed last time, but even then: I have projects that are known to be broken. They are subfolders of one of my workspace folders, so they will always be there and I don't want the extension to attempt anything with them unless I ask it to.

This behavior makes the extension unusable as my default Java extension.

[sid-srini]

Hi @anthonyvdotbe.

As mentioned in #493, we have been tracking issues around this area, and do hope to address this, (as well as #362) in the near future.
We'll update you here once this gets implemented.

Thanks