Email: Allow users to remove recipients from the recipient list

[dospromptman]

Currently, once the send emails action is invoked, the recipient list is immutable (except where it may be filtered because of record visibility or invalid parameters). The user sending the email can not add or remove recipients from the list within the send emails action.

We should allow the user to remove recipients from the list within the send emails action. This would probably be implemented as a row level action when viewing the recipient list in the send emails action and/or as a pill action when recipients are shown as pills.