[MM-32543] - Add ability to send email to admin that users are trying to invite others (#16882)

* [MM-32543] - Add ability to send email to admin that users are trying to join

* Update email template

* Feedback impl-1

* Fix test

* Feedback impl-2

* Fix error

* Feedback impl

* Use 413 status code

* make i18n-extract

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

i18n/en.json

@@ -2606,6 +2606,10 @@
     "id": "api.templates.at_limit_info2",
     "translation": "Alternatively, you can disable users in the Admin Console to open up spots for more users or stay below the free user limit."
   },
+  {
+    "id": "api.templates.at_limit_info5",
+    "translation": "Alternatively, you can disable users in the Admin Console to open up spots for users and stay below the free user limit."
+  },
   {
     "id": "api.templates.at_limit_subject",
     "translation": "Mattermost Cloud User Limit Reached"
@@ -2962,6 +2966,18 @@
     "id": "api.templates.upgrade_mattermost_cloud",
     "translation": "Upgrade"
   },
+  {
+    "id": "api.templates.upgrade_request_info4",
+    "translation": "Because your workspace has reached the user limit for the free version of Mattermost cloud, invitations cannot be sent. Upgrade now to allow more users to join your workspace."
+  },
+  {
+    "id": "api.templates.upgrade_request_subject",
+    "translation": "Mattermost user request upgrade of workspace"
+  },
+  {
+    "id": "api.templates.upgrade_request_title",
+    "translation": "{{ .UserName }} would like to invite members to your workspace"
+  },
   {
     "id": "api.templates.user_access_token_body.info",
     "translation": "A personal access token was added to your account on {{ .SiteURL }}. They can be used to access {{.SiteName}} with your account."
@@ -3446,6 +3462,10 @@
     "id": "api.user.send_sign_in_change_email_and_forget.error",
     "translation": "Failed to send update password email successfully"
   },
+  {
+    "id": "api.user.send_upgrade_request_email.error",
+    "translation": "Failed to send email to user limit notification to admin"
+  },
   {
     "id": "api.user.send_user_access_token.error",
     "translation": "Failed to send \"Personal access token added\" email successfully"
@@ -5730,6 +5750,10 @@
     "id": "app.user.search.app_error",
     "translation": "Unable to find any user matching the search parameters."
   },
+  {
+    "id": "app.user.send_emails.app_error",
+    "translation": "No emails were successfully sent"
+  },
   {
     "id": "app.user.update.find.app_error",
     "translation": "Unable to find the existing account to update."