Add support to specify kernel name in PapermillOperator

[minhthong582000]

This PR adds a kernel_name field to PapermillOperator so we can specify name of kernel to execute the notebook against.
If kernel_name is specifed, papermill ignores kernel name in the notebook document metadata.

---

^ Add meaningful description above

Read the Pull Request Guidelines for more information.
In case of fundamental code change, Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in UPDATING.md.

[potiuk]

I assume python3 is currently an implicit default @minhthong582000 ?

[github-actions]

The PR is likely OK to be merged with just subset of tests for default Python and Database versions without running the full matrix of tests, because it does not modify the core of Airflow. If the committers decide that the full tests matrix is needed, they will add the label 'full tests needed'. Then you should rebase to the latest main or amend the last commit of the PR, and push it with --force-with-lease.

[minhthong582000]

I assume python3 is currently an implicit default @minhthong582000 ?

If kernel_name is None, papermill will look at the notebook document metadata, like:

 "metadata": {
  "celltoolbar": "Tags",
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3" 
  },

Here i'm just using the kernel that i found from this example.

[potiuk]

I assume python3 is currently an implicit default @minhthong582000 ?

If kernel_name is None, papermill will look at the notebook document metadata, like:

 "metadata": {
  "celltoolbar": "Tags",
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3" 
  },

Here i'm just using the kernel that i found from this example.

Ah perfect!

[boring-cyborg]

Awesome work, congrats on your first merged pull request!