Bootstrap cache and groupId fixes

[aloubyansky]

As discussed on the dev list:

• removed everything related to quarkus-deployment-dependency.graph
• move classpath cache from ~/.quarkus to project.basedir/target
• changed groupId of bootstrap from io.quarkus.bootstrap to io.quarkus

[Sanne]

let's be careful here, we're about to merge several out-of-tree extensions.

They all mention <groupId>io.quarkus.bootstrap</groupId>, so depending on order of merges things will need to be adjusted.

[aloubyansky]

Just in case, I won't mind rebasing this one.

[Sanne]

Just in case, I won't mind rebasing this one.

Thanks :) just merged the flyway extension then #1649

[gsmet]

Looks good to me.

[gsmet]

@Sanne did you have any other extensions in mind? I think we can merge now?

[Sanne]

@gsmet +1 to merge, I'll let the other "out of tree" being written extension authors know.

@aloubyansky could you let the mailing list know?

thanks!