users: use generic dests for user CM form, create, and edit dialogs

[tony-tvu]

• Identified the issue which this PR solves.
• Read the CONTRIBUTING document.
• Code builds clean without any errors or warnings.
• Added appropriate tests for any new functionality.
• All new and existing tests passed.
• Added comments in the code, where necessary.
• Ran make check to catch common errors. Fixed any that came up.

Description:
This PR assumes #3660 has already been approved and merged to master branch. This PR updates the UserContactMethod form, create, and edit dialogs to use destinations when the experimental flag is set make start EXPERIMENTAL=dest-types.

Which issue(s) this PR fixes:
part of #2639

Out of Scope:
N/A

Screen





shots:

Describe any introduced user-facing changes:
N/A, behavior should be the same as today, with the exception of Slack now using the team/workspace icon instead of the generic slack icon.

Describe any introduced API changes:
N/A

Additional Info:
N/A

[tony-tvu]

Closing to split into separate PRs.