Data Workflows: allow trigger upserts in favour of creates

[VerstraeteBert]

Description

• Change client.workflows.triggers.create to client.workflows.triggers.upsert, now allowing upserts instead of only creations.
  • Rename cognite.client.data_classes.workflows.WorkflowTriggerCreate to cognite.client.data_classes.workflows.WorkflowTriggerUpsert
  • Rename cognite.client.data_classes.workflows.WorkflowTriggerCreateList to cognite.client.data_classes.workflows.WorkflowTriggerUpsertList

Checklist:

• Tests added/updated.
• Documentation updated. Documentation is generated from docstrings - these must be updated according to your change.
  If a new method has been added it should be referenced in cognite.rst in order to generate docs based on its docstring.
• Changelog updated in CHANGELOG.md.
• Version bumped. If triggering a new release is desired, bump the version number in _version.py and pyproject.toml per semantic versioning.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.22%. Comparing base (3abca3a) to head (158cb2e).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1944   +/-   ##
=======================================
  Coverage   90.22%   90.22%           
=======================================
  Files         135      135           
  Lines       21573    21573           
=======================================
  Hits        19465    19465           
  Misses       2108     2108           

Files with missing lines	Coverage Δ
cognite/client/_api/workflows.py	89.18% <100.00%> (ø)
cognite/client/_version.py	100.00% <100.00%> (ø)
cognite/client/data_classes/__init__.py	100.00% <ø> (ø)
cognite/client/data_classes/workflows.py	94.94% <100.00%> (ø)

... and 2 files with indirect coverage changes