MM-54123 Add group slash command (#24553)

* adding group members to channel initial commit

* adding group to channel functionality along with add new team members

* fixing circular dependency

* fixing e2e and other optimizations

* adding e2e tests for adding group members to channels

* cypress lint

* fixing comments

* adding count to button

* improvements

* adjusting some stuff from PR comments

* remove ability to add user to team, update message for non-team members

* remove adding to team from add groups functionality

* update misspelled variable

* lint and unit test fixes

* add tests, cleanup

* lint fix

* revert package-lock.json

* fixes for cypress tests

* rename TeamInviteBanner to TeamWarningBanner, since invites are no longer allowed

* update for warning

* lint fixes

* cleanup

* fix failing e2e tests

* update slash command for user groups

* revert package-lock

* remove unused function

* update based on feedback

* update tests for last change

* i18n-extract, reorder

* retrieve and display user name

---------

Co-authored-by: Benjamin Cooke <benkcooke@gmail.com>
Co-authored-by: Mattermost Build <build@mattermost.com>

server/i18n/en.json

@@ -918,6 +918,10 @@
     "id": "api.command_invite.channel.error",
     "translation": "Could not find the channel {{.Channel}}. Please use the [channel handle](https://docs.mattermost.com/messaging/managing-channels.html#naming-a-channel) to identify channels."
   },
+  {
+    "id": "api.command_invite.channel_constrained_user_denied",
+    "translation": "This channel is managed by groups.  This user is not part of a group that is synced to this channel."
+  },
   {
     "id": "api.command_invite.desc",
     "translation": "Invite a user to a channel"
@@ -930,10 +934,6 @@
     "id": "api.command_invite.fail.app_error",
     "translation": "An error occurred while joining the channel."
   },
-  {
-    "id": "api.command_invite.group_constrained_user_denied",
-    "translation": "This channel is managed by groups.  This user is not part of a group that is synced to this channel."
-  },
   {
     "id": "api.command_invite.hint",
     "translation": "@[username]... ~[channel]..."
@@ -962,13 +962,28 @@
     "id": "api.command_invite.success",
     "translation": "{{.User}} added to {{.Channel}} channel."
   },
+  {
+    "id": "api.command_invite.successOverflow",
+    "translation": "{{.FirstUser}} and {{.Others}} added to {{.Channel}} channel."
+  },
   {
     "id": "api.command_invite.user_already_in_channel.app_error",
-    "translation": "{{.User}} is already in the channel."
+    "translation": {
+      "one": "{{.User}} is already in the channel.",
+      "other": "{{.User}} are already in the channel."
+    }
+  },
+  {
+    "id": "api.command_invite.user_already_in_channel.overflow",
+    "translation": "{{.FirstUser}} and {{.Others}} others are already in the channel."
   },
   {
     "id": "api.command_invite.user_not_in_team.app_error",
-    "translation": "@{{.Username}} is not a member of the team."
+    "translation": "You can add {{.Users}} to this channel once they are members of the **{{.Team}}** team."
+  },
+  {
+    "id": "api.command_invite.user_not_in_team.messageOverflow",
+    "translation": "You can add {{.FirstUser}} and {{.Others}} others to this channel once they are members of the **{{.Team}}** team."
   },
   {
     "id": "api.command_invite_people.permission.app_error",