Setup mock voice provider for SendVoice action type

Problem

Voice calls show [Not sent - ActionType SendVoice is not a send action] instead of being processed.

Expected Behavior

SendVoice action type should be recognized as a send action and use a mock/development voice provider similar to how SMS and Email work.

Tasks

• [ ] Investigate why SendVoice is not recognized as a send action
• [ ] Create mock voice provider for development
• [ ] Register voice provider in DI
• [ ] Add tests