sortbydeps: include local pkgs in dep graph

Detecting indirect dependencies by traversing a package's entire
dependency tree is prohibitively slow for larger transactions.  Instead
add local packages to the dependency graph.  This additionally requires
delaying dependency ordering for sync operations so that removed
packages may be excluded from dependency detection.

tests/sync012.py was also updated to ensure that the dependency cycle
was actually detected.

Fixes FS#37380

Signed-off-by: Andrew Gregory <andrew.gregory.8@gmail.com>