LIN-736: Merge dvc_dag_PythonOperator.jinja into task_function.jinja

[andycui97]

Description

Merges repeated logic in dvc_dag_PythonOperator.jinja into task_function.jinja.

Changes:

• Rename localpickle to tmpdirpickle to better match the behavior of the serialization flavor.

  • Add CWD pickle flavor

• Remove stages logic in DVC pipeline writer to directly use TaskDefinitions where possible and avoid intermediate task representation specific to DVC.

  • Change lineapy/plugins/jinja_templates/dvc/dvc_dag_StagePerArtifact.jinja to use Task Definitions as well.

• Change dvc_dag_PythonOperator.jinja to use TASK_CODE block generated from the task_function template.

Fixes: LIN-736

Type of change

Please delete options that are not relevant.

• [X] Refactor (non-breaking change which should not change functionality)

How Has This Been Tested?

• Ensure snapshot tests for DVC do not change. DVC output has been prettified so the snapshot diff has a lot of changes which have been verified to be only spacing and formatting changes.

[andycui97]

My. main query here is how does renaming LocalPickle to TmpDirPickle help in the PR. Most probably I'm missing some context here so a sync up would be helpful!

I renamed LocalPickle because it actually describes the newly added CWD pickle flavor. LocalPickle suggests we are using Pickle to a local directory but that doesnt distinguish between using local tmp vs local working directory. I renamed them both so that there is a distinction.