Add Session Affinity toggle to dr-apps CLI

[ben-cutler-datarobot]

This PR does the following:

1. Refactors the create command to handle runtime params consistently with a update_resources rather than a update_num_replicas or a update_cpu_size
2. Refactors the create unit test to cover cases where kwargs such as --replicas is unset
3. Refactors the create unit test to render the multipart data, rather than assume various data blobs are in it.
4. Adds a --use-session-affinity boolean flag for whether session affinity is set or not in the app.

[engprod-2]

The Needs Review labels were added based on the following file changes.

Team @datarobot/applications (#applications) was assigned because of changes in files:

drapps/create.py
drapps/helpers/custom_app_sources_functions.py
setup.cfg
tests/cli/test_create.py

If you think that there are some issues with ownership, please discuss with C&A domain at #sdtk slack channel and create PR to update DRCODEOWNERS\CODEOWNERS file.

[raulpineda]

This seems like a breaking change to me, unless we keep the update_num_replicas and update_cpu_size and alias them to update_resources I think this needs more than a patch version bump.

@demchukilya thoughts?

[demchukilya]

@raulpineda From my perspective this part looks fine.

update_num_replicas and update_cpu_size -- are internal implementations and it's not expected, that user will user those functions directly. User interacts only with CLI commands and from this point only change is added new argument --use-session-affinity.

I am a bit not happy that we are using cpu-size instead of resource bundle, because in most cases not CPU but RAM is biggest limitation factor, but it looks like this is here for long enough.

[engprod-2]

Label Needs Review: Applications was removed because @demchukilya is part of Applications domain.