Add Generator for RegisterServices

[zeripath]

This PR adds a reusable services generator that will create an init import file.

Signed-off-by: Andrew Thornton art27@cantab.net

[zeripath]

So the generated file probably should be .gitignored

And we may need to make the generator a little bit more general to permit passing in the base package name.

It may also need some globbing support to make the excludes and includes a bit better too.

However it's pretty usable as is.

What's really interesting is the possibilities for this beyond this use.

modules/queue could be restructered with that directory simply containing the interfaces and a registry of known implementations. The manager would be moved to manager along with a generated provider importer, and the providers all within their own directories and so on