peer-or-repo: move the object setup in its own function
The `_peerorrepo` function is problematic, because it can build different types
of object (repository and peer). This make it hard to adjust the arguments to
the type of object we needs. So this patch start a series of change to create
peer and repo without going through a common function.
We move the part of the function doing object setup it its own function to make
it simpler to reuse in others contexts.
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