Support dataset timetable

[AppKiv]

support DatasetOrTimeSchedule
add processing key "timetable" for schedule with key "datasets"

example:

  schedule:
    datasets: "((s3://dataset_custom_1 & s3://dataset_custom_2) | s3://dataset_custom_3)"
    timetable: 
      __type__: airflow.timetables.trigger.CronTriggerTimetable
      cron: "0 1 * * 5"
      timezone: UTC

[codecov-commenter]

Codecov Report

❌ Patch coverage is 69.23077% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.49%. Comparing base (ca9914e) to head (2472727).

Files with missing lines	Patch %	Lines
dagfactory/dagbuilder.py	69.23%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #599      +/-   ##
==========================================
- Coverage   93.77%   93.49%   -0.29%     
==========================================
  Files          13       13              
  Lines        1125     1137      +12     
==========================================
+ Hits         1055     1063       +8     
- Misses         70       74       +4     

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