Project CRaC to track openjdk/jdk

[Anton Kozlov]

Project CRaC has been developed for a while and has a considerable interest in
the Java Community [1].  At this point, we need even further spread of the API,
which is not possible without CRaC API eventually appearing in the mainline.

Thus, I propose to base future development on top of the openjdk/jdk, tracking
master branch.  This will also make developers' life a bit easier as we'll
automatically get the most recent fixes.

The main focus of the development will be the new master-crac branch.  But I
also propose to keep a branch for jdk17-crac, with a snapshot of the state
before the merge of the openjdk/jdk, plus occasional backports of breaking API
changes.  So, the jdk17-crac still be a version suitable for wider try-out.

At the moment we have a pretty long queue of PRs and unfinished works. I
propose to concentrate on the long-standing PRs, and topics we've started
working on, e.g. configurable CPU features, Context behaviors, and
FileDescriptors. Before transition, we need to create an EA build that is not
worse than the previous one [1] in terms of quality and usability. Exceptions
are possible: we may accept a new enhancement, or postpone an existing PR if it
is decided risky enough. The decision will be done on a case by case basis.

I'll announce dates when we'll be closer to the finish with PRs.

[1] https://github.com/openjdk/crac/tree/crac-17+5

Thanks,
Anton