[#84299082] Add Xten library creation request type
[#84299082] Add Xten plate purposes
[#84299082] Add plate purpose relationships

Plate purpose relationships between new purposes
New classes for later expansion
Move purpose creation into standard seed templates
[#84299082] Expose request type key in pool info

We expose the request type key to help use determine
what plate is needed next. Pool and Pippin use
target_tube_purpose which isn't available to us here
as we have no target tube.

We use key rather than name, as despite the
inconsistency with a similar technique in the Generic
Lims, it is a more robust choice. Uuid would be even
more robust, but is not human readable.
[housekeeping] Add tag plates to working setup task
[#84299082] Lib Norm purpose is an InitialDownstreamPlate
[#84299082] Lib Norm 2 plate connects requests
The lib norm 2 plate connecs upstream library creation requests
and passes them on transition to passed.
Resolve schame merge conflict
Merge pull request #947 from JamesGlover/ss164_outline_of_xten_library_creation

Ss164 outline of xten library creation