insane: Split do_package_qa into a separate task (from do_package)

insane: Split do_package_qa into a separate task (from do_package)

Its possible to run the package QA checks as a separate task rather than
as part of the do_package task. This offers more parallelism but the
fact that made me propose this is that ideally we'd like to access
pkgdata to help add new tests and to do that, we need to run later in
the task list. We also need to add in RDEPENDS to the task which apply
to do_package_write_* but not do_package. See the subsequent patches
for why this is desireable.

If we split into a separate task, we need to add in calls to read
the sub package data, build the cache structure used by do_package and
cover the task with sstate (which is empty and just acts as a stamp
saying it passed package QA). We also need to handle our own
dependencies.

(From OE-Core rev: d31f75a72cb2322f753d945da86d5f3287eef06b)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>