Adding a tag field to handle OMERO tags

[Rdornier]

Feature request

Issue Metadata fields are perfectly suitable for OMERO Key-value pairs but there is no way to propertly handle OMERO tags in QuPath.

Description of the solution As tags are very useful in OMERO to search for images, it could be great to also have a tag field in QuPath.

Tag field attributes

• value (unique => no duplicate possible)
• used to sort the images within the project
• maybe other attributes mirorred from the Metadata field object that I'm not aware of.