LIMS-1334: Allow selection of plate samples already in a group

JIRA ticket: LIMS-1334

Summary:

Allow a plate sample that is already in a group to be selected for adding to a new group

Changes:

Maintain a list of manually selected samples, pass that down to the plate view
Use this list to decide whether a click is a select or deselect
Use uniqBy instead of concatenating a difference list to return valid samples (this list includes those already in groups)

To test:

Open proposal nt37104, go to Sample Groups, then Create Sample Group
Select a shipment and a plate (with no coloured samples)
Select a few samples and create a group with a name, check the view on the Sample Groups page that this has worked correctly
Go back to Create Sample Group, use the same shipment and plate, some samples should now be blue to show they are already in a group
Check that clicking on blue samples turns them green, and clicking again turns them blue again
Select some previously blue samples and some previously grey samples and create a group.
Use the row select, column select, and select all buttons to create more groups. Each should toggle green and blue or grey.
Check each group has been created with the correct samples.

DiamondLightSource / SynchWeb