Add support for nested metadata of sample characteristics

[nguyenlinhlinh]

Description

See issue

Motivation

See issue Background on use case, changes needed

Tests included/Docs Updated?

• [ ] Included for each change/fix?
• [ ] Passing? (Merge will not be approved unless this is checked)
• [ ] Docs updated?
• [ ] New packages used/requires npm install?
• [ ] Toggle added for new features?