This commit modifies the UI for Post Reply when an Agent views a Ticket.

- Change To dropdown to have different reply types
	- Reply to All
	- Reply to User
	- Reply to Collaborators
	- Reply to BCC
- Add a help tip for the new reply types
- Set the reply type selected based on the last user respondent
	- Reply to Collaborator by default or if the last message is from the ticket user or a CC collaborator
	- Reply to BCC if the last message is from a BCC user
- Put User, CC, and Bcc fields below and indented as appropriate (User field is readonly)
- Add a new flag to Agent responses to show which reply type they selected. Put the flag on Agent thread entries