Initial refactor of create edges.
Initial refactor of create edges.

This is part of the refactoring to improve create edges time.

- Remove usage of multiprocess now that channel creation is fast
- Remove alive tracks set, and let sqlite filter (via index).
- Refactor edge creation into function.

Signed-off-by: Keith Rothman <1bc19627a439baf17510dc2d0b2d250c96d445a5@users.noreply.github.com>

SymbiFlow/symbiflow-arch-defs,SymbiFlow/symbiflow-arch-defs