[fixed #45218563] Sample manifests can't clear accession no.
[#45378543] Avoid loading all requests on batches
[fixes #45401941] Submissions can have mixed reference genomes
[#45502053] Update number of samples for register
Merge pull request #749 from JamesGlover/45378543_potential_memory_leaks_remain

[#45378543] Avoid loading all requests on batches
Merge pull request #750 from JamesGlover/45401941_submissions_don't_need_samples_with_the_same_reference_genome

[fixes #45401941] Submissions can have mixed reference genomes
Merge pull request #751 from JamesGlover/45502053_sample_registration_increase_number_of_samples_allowed_per_spreadsheet_to_384

[#45502053] Update number of samples for register
Merge pull request #752 from JamesGlover/45218563_sample_manifests_should_not_be_able_to_unset_accession_numbers

[fixed #45218563] Sample manifests can't clear accession no.