dest/escalation-policies: use destinations for EP step create dialog

[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 adds an escalation policy step create dialog component which utilizes generic destinations when experimenta flag is set to dest-types. This PR cannot be merged until #3717 has been approved and merged first. After #3717 has been merged, the amount of code line changes for this PR should fall below 500. Along with component tests, a playwright integration test has been added to verify we can create an EP step with multiple actions.

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

Out of Scope:
N/A

Screenshots:

Describe any introduced user-facing changes:
The UI will no longer use Material-UI's accordion component when creating a new escalation policy step. Instead, it will utilize a simplified menu selector where users will view and add a single action at a time.

Describe any introduced API changes:
N/A

Additional Info:
N/A