added mod mail thread notification, if a user initiates a mod mail thread

added the concept of a mod mail role, these are roles being pinged when a thread is opened, and they also are able to execute mod mail related commands
fixed past thread count in mod mail header
added convenience method to allow a role to execute a whole feature

abstracto-application/template-config/src/main/resources/templates/en_US/commands/modmail/setModMailRole/help/setModMailRole_description_en_US.ftl

@@ -0,0 +1 @@
+text

abstracto-application/template-config/src/main/resources/templates/en_US/commands/modmail/setModMailRole/help/setModMailRole_long_help_en_US.ftl

@@ -0,0 +1 @@
+text

abstracto-application/template-config/src/main/resources/templates/en_US/commands/modmail/setModMailRole/help/setModMailRole_usage_en_US.ftl

@@ -0,0 +1 @@
+setModMailRole <role>

abstracto-application/template-config/src/main/resources/templates/en_US/modMail/modmail_notification_message_description_en_US.ftl

@@ -0,0 +1 @@
+The thread concerns ${user}.

abstracto-application/template-config/src/main/resources/templates/en_US/modMail/modmail_notification_message_title_en_US.ftl

@@ -0,0 +1 @@
+A new mod mail thread has been opened.

abstracto-application/template-config/src/main/resources/templates/en_US/modMail/modmail_thread_header_embed_description_en_US.ftl

@@ -1,3 +1,3 @@
 This is a mod mail thread concerning ${user}.
 The user has the roles ${roles} and joined on ${joinDate}
-There were ${threadCount} threads in the past.
+There were ${pastModMailThreadCount} threads in the past.