Add and update KFP processor tests

[ptitzler]

Closes #3002

Signed-off-by: Patrick Titzler ptitzler@us.ibm.com

What changes were proposed in this pull request?

• Moved tests from elyra/tests/pipeline/kfp/test_processor_kfp.py that were not KFP specific to elyra/tests/pipeline/test_processor.py
• Added new fixtures and supporting functions in elyra/tests/pipeline/kfp/conftest.py to simplify test implementation
• Added tests to elyra/tests/pipeline/kfp/test_processor_kfp.py
• Improved existing tests in elyra/tests/pipeline/kfp/test_processor_kfp.py
• Created new KFP test artifacts in elyra/tests/pipeline/resources/test_pipelines/kfp

How was this pull request tested?

• pytest -vv elyra/tests/pipeline/kfp/test_processor_kfp.py
• pytest -vv elyra/tests/pipeline/test_processor.py

Developer's Certificate of Origin 1.1

   By making a contribution to this project, I certify that:

   (a) The contribution was created in whole or in part by me and I
       have the right to submit it under the Apache License 2.0; or

   (b) The contribution is based upon previous work that, to the best
       of my knowledge, is covered under an appropriate open source
       license and I have the right under that license to submit that
       work with modifications, whether created in whole or in part
       by me, under the same open source license (unless I am
       permitted to submit under a different license), as indicated
       in the file; or

   (c) The contribution was provided directly to me by some other
       person who certified (a), (b) or (c) and I have not modified
       it.

   (d) I understand and agree that this project and the contribution
       are public and that a record of the contribution (including all
       personal information I submit with it, including my sign-off) is
       maintained indefinitely and may be redistributed consistent with
       this project or the open source license(s) involved.

[elyra-bot]

Thanks for making a pull request to Elyra!

To try out this branch on binder, follow this link:

[kiersten-stokes]

So much cleaner now! This is great 👏