Reconcile the base classes with the three forks and bring the missing ones home

Problem/Motivation

The module exists as four independent forks — 73 resources on one site, 45 on another, 28 on a third and 42 in this copy — and the base classes drifted apart. One fork has MyrestResourceFileUpload, which this copy does not have at all, and a module on that site already extends it. Any base class the generator will emit subclasses of has to be the union of what the forks actually need, decided once, or the divergence simply moves into the generated code.

Proposed resolution

• Diff the base classes of the four forks method by method and record the differences: present here only, present there only, same name and different behaviour.
• Bring over what belongs to everyone, starting with MyrestResourceFileUpload.
• For a method that differs in behaviour, decide which one is correct and note why in the issue — this is where old bugs are, not just old styles.
• Leave anything site-specific alone; it is destined for the manual folder, not for the core.

Remaining tasks

Everything. Produces the input for the rewrite of the base classes by kind of resource.