Add a button for adding preselected tag to the texter UI

[ajohn25]

Is your feature request related to a problem? Please describe.
Organizations that use tags for managing common sets of data like wrong numbers want to be able to add a tag to a conversation with a single click.

Describe the solution you'd like
Add a button to the texter UI which allows the texter to add that tag to the conversation with a single click. The tag that is applied is preselected by admins.

Describe alternatives you've considered
See initial thoughts in #1591