Proto,WASM: Remove the Gather_floppies layer

Context

The Gather_floppies instrumentation was introduced in the early days (👴) of the WASM PVM, to tackle the limitations of Tezos wrt. the origination operation.

This instrumentation can now be reimplemented in WASM, and so we remove the Gather_floppies module.

After that, the origination boot sector becomes the output of your favorite compiler 🎉 which is pretty nice if you ask me.

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