Merge recipients into one field and hide the email field unless explicitely requested

[SpookyBoy99]

It is a two part proposal:

• By adding the board to the dropdown list of recipients, it is clear that one must select at least one recipient and improves UI clarity overall by using one single method of selecting a recipient (instead of checkbox and dropdown w/ checkboxes)
• Hiding the email field unless a field is checked that indicates that the user want to be kept in the loop will remove UI clutter, make it clear by design language that it is not a required field (instead of due text) and allow to clean up the label (which now has to state very explicitly that this is an optional field and must not be filled in if one wishes to remain anonymous)