move and rename 'binding, bridging'

[dosumis]

This is a compound function - it binds more than one macromolecules (possible edge case - binding to polar head group of a phospholipid).

• [ ] Move under whatever 'molecular component function' ends up being called.
• [ ] Rename -> (macro)molecular adaptor (activity)

(Becomes a structural molecule via part_of some organization)

[pgaudet]

Fixed in the MF factor work with @thomaspd