* rename GlobalValidationSchedule to GlobalValidationData
* guide: update candidate descriptor to contain validation data hash
* guide: add note in inclusion module about checking validation data hash
* primitives: update CandidateDescriptor to contain new hash
* fix payload computation
* add helpers for computing validation data to runtime modules
* guide: note routines
* inclusion: check validation data hash and fix local_validation_data bug
* add a case to candidate_checks and improve that test substantially
* bump versions
* address review comments
* add a test for including code upgrade
* bump kusama version
* bump westend & polkadot versions