classes/*_rpm: integrate Smart into RPM filesystem construction

classes/*_rpm: integrate Smart into RPM filesystem construction

Use Smart to construct the root filesystem for images and the contents
of SDKs rather than the custom scripts around rpm we had previously.
This ensures the result when producing an updated image will be the
same as upgrading to the same package versions from an older image on
the target, as well as allowing us to remove a substantial amount of
code making the rpm classes much easier to follow.

Some bugfixes from Bogdan Marinescu <bogdan.marinescu@intel.com>.
SDK implementation and testing as well as a number of bugfixes from
Mark Hatle <mark.hatle@windriver.com>.

(From OE-Core rev: a726ae7c032fac1aa49ce34180fa2ed2dcaf87d3)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>