devtool: deploy: fix preservation of symlinks and permissions/ownership

devtool: deploy: fix preservation of symlinks and permissions/ownership

It turns out that scp can't be used to copy symlinks because it follows
them instead of copying them, and this is by design (since it emulates
rcp which also behaved this way); the unfortunate result is that
symlinks that point to valid files on the host translate into the host
file being copied to the target (yuck).  The simplest alternative that
does not have this undesirable behaviour is to use tar and pipe it over
ssh.

At the same time, it would be even better if we properly reflect file
permissions and ownership on the target that have been established
within the pseudo environment. We can do this by executing the copy
process under pseudo, which turns out to be quite easy with access to
the pseudo environment set up by the build system.

Fixes [YOCTO #7868].

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>