Draft: direct ticket transfers from implicit to smart contracts (behind feature flag)

Context

See https://hackmd.io/@SN2T3ARoSc6_TDWxXDobJg/BJsQS4kJT

This is an attempt at implementing, behind a feature flag, the first item of the proposal.

It's currently incomplete because the ticket table update for the transfer is not yet done. The added test fails for this reason.

The point of this MR was to measure the technical difficulty of the proposal, it seems not trivial to do because updating the ticket table requires type information about the transferred tickets and that information is not available at that time.

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