Add option to configure termset in IE demo

[vmenger]

Describe the feature
In the information extraction demo app, it would be nice to be able to interactively define the termset (i.e. the concepts and terms) in the UI. This way, we can also use it to demo the entity matching capabilities, rather than just a static set of terms.

A use case for the feature
A user wants to test/learn how the rule based entity matcher works.

Would you like to be involved in development?
Yes

Additional context
N/a