[infra] Overhaul gen_tasks_logic

- Add jobBuilder and taskBuilder for convenience.
- Add parts type with convenience matching funcs.

Change-Id: I8213a1e3742d055515e7b8520b2dec0c06c6f2d3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/275076
Commit-Queue: Eric Boren <borenet@google.com>
Reviewed-by: Ben Wagner aka dogben <benjaminwagner@google.com>
6 files changed