Due to 'mass_mailing_sms' inheriting mailing.mailing from
'mass_mailing', activities for these two modules would show up as one
"Mass Mailing" line in the systray. This commit adds additional logic
to remove this "Mass Mailing" line and replace it with 2 lines: "Email
Marketing" and "SMS Marketing" with their appropriately matching module
icon. For consistency, when only the 'mass_mailing' module is installed,
it will still display "Email Marketing".

Task: 2169498