feat(factory): Support Custom Client Types

[AlexCuse]

Enable registration of custom type with factory and use on client
creation if configured type doesn't match any predefined option.

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

If your build fails due to your commit message not passing the build checks, please review the guidelines here: https://github.com/edgexfoundry/go-mod-messaging/blob/master/.github/Contributing.md.

What is the current behavior?

Only predefined messagebus client types are supported

Issue Number:

#74

What is the new behavior?

Using messaging.RegisterCustomType a factory function can be registered to create clients for a given configured type. This is stored in a map that is checked before returning error if the configured type does not match any predefined option.

Does this PR introduce a breaking change?

• Yes
• No

New Imports

• Yes
• No

Specific Instructions

Are there any specific instructions or things that should be known prior to reviewing?

Other information

[codecov-io]

Codecov Report

Merging #75 into master will decrease coverage by 0.53%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #75      +/-   ##
==========================================
- Coverage   83.33%   82.79%   -0.54%     
==========================================
  Files          14       14              
  Lines         504      436      -68     
==========================================
- Hits          420      361      -59     
+ Misses         64       55       -9     
  Partials       20       20              

Impacted Files	Coverage Δ
...nternal/pkg/redis/streams/configuration_options.go	60.00% <ø> (-6.67%)	⬇️
pkg/types/message_envelope.go	100.00% <ø> (ø)
internal/pkg/redis/streams/client.go	94.80% <100.00%> (-0.49%)	⬇️
messaging/factory.go	86.66% <100.00%> (+3.33%)	⬆️
pkg/types/host_info.go	60.00% <0.00%> (-11.43%)	⬇️
internal/pkg/zeromq/subscriber.go	55.55% <0.00%> (-4.45%)	⬇️
internal/pkg/zeromq/client.go	75.72% <0.00%> (-2.05%)	⬇️
internal/pkg/mqtt/client_options.go	85.29% <0.00%> (-0.82%)	⬇️
... and 7 more

---

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[lenny-goodell]

@AlexCuse , we are in code freeze for Hanoi, so I have switch this PR to draft and marked in on-hold.

[AlexCuse]

Just wanted to check in to see if this needs anything else. Forgot about it for awhile but digging back in here today.

[lenny-goodell]

Nope, just hadn't got back to looking at it. Will do now.