R1:b8b7bf8ad9ec

Provide `phragment.getstate` and `phragment.getpatch` Conduit methods

Summary:
This provides a `phragment.getstate` and a `phragment.getpatch` Conduit method.

`phragment.getstate` - This returns the current state of the fragment and all of it's children.

`phragment.getpatch` - This accepts a base path and a mapping of paths to hashes. The mapping is for the caller to specify the current state of the files it has. This returns a list of patches that the caller needs to apply to it's files to get to the…