[WIP] ✨ Generation of typed apply clients using upstream generator

[JoelSpeed]

This integrates the upstream applyconfig generator into controller-tools to allow generation of ApplyConfig style types from custom API types.

The aim here is to provide the pointer style structs that could then be passed to an Apply style method for using server side apply.

Setting this up as a WIP PR for now, current TODO list:

• [x] Work out if there's any extra stuff here that's not needed
• [x] Work out how to test this without the hack adding cronjob testdata to the go.mod
• [ ] Do we need OpenAPI schema/do we need the extract functions?
• [x] General review of code and cleanup - this was quite hacky when I started the branch
• [ ] How would a user want this integrated into their project?