imagetest-qemu.bbclass, qemuimage-testlib: add support for more FSTYPES
qemuimage-testlib hardcodes ext3 as fs type. This adds support for more
images types which are supported by runqemu: ext[234]/jffs2/btrfs.
I've skipped (for now) vmdk (which qemu can boot) because:
- we don't have network on images without connman because of the way
runqemu starts vmdk images (can't pass kernel args for network config)
- qemuimage-testlib-pythonhelper relies on '192.168' being in the output of
ps to return the pid
Signed-off-by: Stefan Stanacar <stefanx.stanacar@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
