[patching] Allow to include features in Hot Fix patches

Currently we can patch bundles in hot fixes (as well as files, but this is rarely used) - the only thing we couldn't patch were features (like adding new <bundle> to a <feature>):

id = my-patch-5
bundle.0 = mvn:org.jboss.fuse/fuse-something/1.2.0
bundle.0.range = [1.1,1.2)
bundle.count = 1

I have an idea to patch features as well.