Option for creating multiple PRs simultaneously

[whitews]

For samples belonging to the same panel but different sites, allow an option in the process request wizard for creating multiple jobs simultaneously split by site. Maybe the best place for this is in the first step of the PR wizard, where if samples from multiple sites are shown, the user is presented with a check box to automatically split the jobs by site. If this is selected, the PR label should be appended with the site name.