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/abstracto-modules/modmail/modmail-impl/src/main/resources/config/modmail.properties

@@ -1,3 +1,3 @@
-abstracto.postTargets.modmail=modmaillog
+abstracto.postTargets.modmail=modmaillog,modmailping
 abstracto.emoteNames.readReaction=readReaction
 abstracto.defaultEmotes.readReaction=\uD83D\uDC40

abstracto-application/abstracto-modules/modmail/modmail-impl/src/main/resources/templates/modmail/modmail_notification_message_embed_en_US.ftl

@@ -0,0 +1,19 @@
+{
+  "author": {
+    "name": "${threadUser.member.effectiveName}",
+    "avatar":  "${threadUser.member.user.effectiveAvatarUrl}"
+  },
+  "title": {
+    "title": "<#include "modmail_notification_message_title">"
+  },
+  "color" : {
+    "r": 200,
+    "g": 0,
+    "b": 255
+  },
+  <#assign user>${threadUser.member.effectiveName}#${threadUser.member.user.discriminator}(${threadUser.member.user.id})</#assign>
+  "description": "<#include "modmail_notification_message_description">"
+  <#if roles?size gt 0>
+  ,"additionalMessage": "<#list roles as role>${role.role.asMention}<#sep>,</#list>"
+  </#if>
+}

abstracto-application/abstracto-modules/modmail/modmail-impl/src/main/resources/templates/modmail/modmail_thread_header_embed_en_US.ftl

@@ -11,6 +11,5 @@
   <#assign user>${threadUser.member.effectiveName}#${threadUser.member.user.discriminator} (${threadUser.member.user.id})</#assign>
   <#assign joinDate>${threadUser.member.timeJoined}</#assign>
   <#assign roles><#list threadUser.member.roles as role>${role.asMention}<#sep>,<#else>No roles</#list></#assign>
-  <#assign threadCount>3</#assign>
   "description": "<#include "modmail_thread_header_embed_description">"
 }