feat: Add task group to task class

[zhongjiajie]

Brief Summary of The Change

   extract = Shell(
      name="extract",
      command="echo 'Some extract command here'",
      task_group_id=1,
      task_group_priority=123
   )

fix: #106

Pull Request checklist

I confirm that the following checklist has been completed.

• [x] Add/Change test cases for the changes.
• [x] Add/Change the related documentation, should also change docs/source/config.rst when you change file default_config.yaml.
• [x] (Optional) Add your change to UPDATING.md when it is an incompatible change.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 90.75%. Comparing base (00c6ba4) to head (2e2caeb). Report is 21 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #114 +/- ## ======================================= Coverage 90.75% 90.75% ======================================= Files 63 63 Lines 2314 2316 +2 ======================================= + Hits 2100 2102 +2 Misses 214 214 ``` | [Flag](https://app.codecov.io/gh/apache/dolphinscheduler-sdk-python/pull/114/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/apache/dolphinscheduler-sdk-python/pull/114/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache) | `90.75% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache#carryforward-flags-in-the-pull-request-comment) to find out more.

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