Proto/CLST: add transfer entrypoint

What

Implements the transfer entrypoint from FA2.1 standard with a basic permission policy from_ == sender. Standard permission policy will be implemented later as tracked in #8214

Implements #8189 (closed).

Tests will come in a future MR, cf #8222

Why

How

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