DAC: Implement Operating modes

Follows !7971 (merged) Closes #4613 (closed) #4750 (closed) #4897 (closed) #4681 (closed)

TODO:

• Write integration tests for operating modes
• Factor Handlers to separate module
• Improve type safety (deferred to !8032 (merged))

Context

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR