[#43563493] Basic support for cross study pooling

This allows the submission of multiple orders in a
submission. However for MX requests it generates a
sequencing request per order.
[#43563493] Sequencing lanes generated per-submission
[#43563493] Ensure errors prezented to user.
[#43563493] Requests from mx should have no study
[#43563493] Multiple projects can't be mixed
[#43563493] Fix up broken tests
[#43563493] Re-disables interface

Re-impliments the blocks. Remove this commit to
fully enable XSP.
Merge pull request #744 from JamesGlover/43563493_cross_study_pooling

43563493 cross study pooling