Keep entity selected when switching to 'subtype'

[danielfrees]

When switching from 'Type' to 'Subtype' annotations, entities are automatically deselected, making it super awkward to annotate both of these things at the same time for a single entity and slowing down workflow.

Would recommend altering the source code for Knowledge studio to keep an entity selected (if it is already), when switching to 'Subtype' mode

[danielfrees]

I would happily help with the code if needed! Just slack me @Daniel.Frees@ibm.com!