LIMS-1550: Add 'Mark Dispensing' button to plate well view

[ndg63276]

JIRA ticket: LIMS-1550

Summary:

We need a way to store the dispensing location for each well in a plate. This PR adds buttons to mark that point manually, edit it, and delete it, and will also display the currently selected location. The location is stored in the BLSample.positionId field.

Changes:

• Add 2 new buttons, 'Mark Dispensing' and (initially hidden) 'Delete'
• Manage the logic between the new buttons and the existing 'Mark Point' and 'Mark Region' buttons
• Insert or update the dispensing position in the database (the delete button updates the x/y/z positions to null)
• Display the dispensing position as a white circle, to distinguish it from subsamples

To test:

• Go to proposal nt37104, go to /containers, then click on any plate with subsamples
• Go to a well with subsamples
• Check the 'Mark Point', 'Mark Region' and 'Mark Dispensing' buttons turn to 'Finish' or 'Cancel' buttons when clicked, but only one can be active at once
• Click 'Mark Dispensing' and then click on the well, check a white circle appears to display where you clicked
• Check the white circle remains in place after a refresh, and after zooming in and out
• Check the BLSample.positionId field and corresponding Position.posX/Y fields are populated in the database
• Repeat the process, check the position updates on screen and in the database
• Click 'Mark Dispensing' and then click 'Delete', check the white circle disappears, check the posX/Y values are now null