Restream.io: Manage Broadcast feature

[SoftwareArchitector]

Description

This adds a "Manage Broadcast" feature (similar to YouTube's) for Restream.io service.

Motivation and Context

This feature improves integration with Restream.io by allowing the user to select an event (pre-created on Restream.io) to start a broadcast. Without this feature, broadcasts can only be started in the default event, limiting flexibility.

How Has This Been Tested?

After connecting a Restream account, a "Manage Broadcast" button will appear, allowing the user to select an existing Restream event. Once an event is selected, the "Start Streaming" button will initiate the stream in the chosen event.

Types of changes

• New feature (non-breaking change which adds functionality)
• Tweak (non-breaking change to improve existing functionality)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.