Add JDK Profiles

Currently, my rough conception of JDK profiles is **a set of commonly-used-together dependencies along with all supporting JDK modules bundled together in a runtime**.

For example, here are a couple of profile ideas:
- `desktop-javafx` containing everything necessary for a JavaFX desktop application.
- `spring` containing the essentials for a Spring application. (I don't know much about Spring, but I think there is a conventional set of dependencies that everyone uses).
- `server-hibernate` containing JPA, Hibernate, C3P0, etc...

This could partially solve the problem of jlink.online being slow because the runtime profiles would be pre-generated and stored. Then, if some profile fits your application, you could download a runtime profile instantly. Otherwise, you would have to manually specify your dependencies and wait for the runtime to be generated the normal way.

Maybe this would be a good place for @karianna to also expand on his idea of JDK profiles.