Allow explicitly specified kind to take precedence.

[rabbah]

Fixes #3845. See issue for details. The patch allows an explicitly specified kind on action create/update to take precedence.

Description

Related issue and scope

• I opened an issue to propose and discuss this change (WskRestOperation does not properly set the exec kind even when one is specified #3845)

My changes affect the following components

• API
• Controller
• Message Bus (e.g., Kafka)
• Loadbalancer
• Invoker
• Intrinsic actions (e.g., sequences, conductors)
• Data stores (e.g., CouchDB)
• Tests
• Deployment
• CLI
• General tooling
• Documentation

Types of changes

• Bug fix (generally a non-breaking change which closes an issue).
• Enhancement or new feature (adds new functionality).
• Breaking change (a bug fix or enhancement which changes existing behavior).

Checklist:

• I signed an Apache CLA.
• I reviewed the style guides and followed the recommendations (Travis CI will check :).
• I added tests to cover my changes.
• My changes require further changes to the documentation.
• I updated the documentation where necessary.

[rabbah]

Going to address this as part of #3840.