SMTP: Update email templates to include populated <title> tag (#61430)

* add .TemplateData property to data in order to populate template <title> tags with the compiled subject value

* update all templates

* re-enable integration test and update implementation to check changes

* chore: fmt

* add HiddenSubject template func and update text templates

* slight performance improvement, only execute subject template once

* update template I missed

---------

Co-authored-by: Gilles De Mey <gilles.de.mey@gmail.com>

emails/templates/invited_to_org.mjml

@@ -2,7 +2,7 @@
   <mj-head>
     <!-- ⬇ Don't forget to specifify an email subject! Use the HTML comment below ⬇ -->
     <mj-title>
-      {{ Subject .Subject "{{ .InvitedBy }} has added you to the {{ .OrgName }} organization" }}
+      {{ Subject .Subject .TemplateData "{{ .InvitedBy }} has added you to the {{ .OrgName }} organization" }}
     </mj-title>
     <mj-include path="./partials/layout/head.mjml" />
   </mj-head>

emails/templates/invited_to_org.txt

@@ -1,4 +1,4 @@
-[[Subject .Subject "[[.InvitedBy]] has added you to the [[.OrgName]] organization"]]
+[[HiddenSubject .Subject "[[.InvitedBy]] has added you to the [[.OrgName]] organization"]]
 
 You have been added to [[.OrgName]]
 

emails/templates/new_user_invite.mjml

@@ -2,7 +2,7 @@
   <mj-head>
     <!-- ⬇ Don't forget to specifify an email subject below! ⬇ -->
     <mj-title>
-      {{ Subject .Subject "{{ .InvitedBy }} has invited you to join Grafana" }}
+      {{ Subject .Subject .TemplateData "{{ .InvitedBy }} has invited you to join Grafana" }}
     </mj-title>
     <mj-include path="./partials/layout/head.mjml" />
   </mj-head>

emails/templates/new_user_invite.txt

@@ -1,4 +1,4 @@
-[[Subject .Subject "[[.InvitedBy]] has invited you to join Grafana"]]
+[[HiddenSubject .Subject "[[.InvitedBy]] has invited you to join Grafana"]]
 
 You're invited to join [[.OrgName]]
 

emails/templates/ng_alert_notification.mjml

@@ -2,7 +2,7 @@
   <mj-head>
     <!-- ⬇ Don't forget to specifify an email subject below! ⬇ -->
     <mj-title>
-      {{ Subject .Subject "{{ .Title }}" }}
+      {{ Subject .Subject .TemplateData "{{ .Title }}" }}
     </mj-title>
     <mj-include path="./partials/layout/head.mjml" />
     <!-- Summary of the email contents, this will go in the email preview -->

emails/templates/ng_alert_notification.txt

@@ -1,4 +1,4 @@
-[[Subject .Subject "[[.Title]]"]]
+[[HiddenSubject .Subject "[[.Title]]"]]
 
 [[.Title]]
 ----------------

emails/templates/reset_password.mjml

@@ -2,7 +2,7 @@
   <mj-head>
     <!-- ⬇ Don't forget to specifify an email subject below! ⬇ -->
     <mj-title>
-      {{ Subject .Subject "Reset your Grafana password - {{.Name}}" }}
+      {{ Subject .Subject .TemplateData "Reset your Grafana password - {{.Name}}" }}
     </mj-title>
     <mj-include path="./partials/layout/head.mjml" />
   </mj-head>

emails/templates/reset_password.txt

@@ -1,4 +1,4 @@
-[[Subject .Subject "Reset your Grafana password - [[.Name]]"]]
+[[HiddenSubject .Subject "Reset your Grafana password - [[.Name]]"]]
 
 Hi [[.Name]],
 

emails/templates/signup_started.mjml

@@ -2,7 +2,7 @@
   <mj-head>
     <!-- ⬇ Don't forget to specifify an email subject below! ⬇ -->
     <mj-title>
-      {{ Subject .Subject "Welcome to Grafana, please complete your sign up!" }}
+      {{ Subject .Subject .TemplateData "Welcome to Grafana, please complete your sign up!" }}
     </mj-title>
     <mj-include path="./partials/layout/head.mjml" />
   </mj-head>

emails/templates/signup_started.txt

@@ -1,4 +1,4 @@
-[[Subject .Subject "Welcome to Grafana, please complete your sign up!"]]
+[[HiddenSubject .Subject "Welcome to Grafana, please complete your sign up!"]]
 
 Complete the signup
 

emails/templates/welcome_on_signup.mjml

@@ -2,7 +2,7 @@
   <mj-head>
     <!-- ⬇ Don't forget to specifify an email subject below! ⬇ -->
     <mj-title>
-      {{ Subject .Subject "Welcome to Grafana" }}
+      {{ Subject .Subject .TemplateData "Welcome to Grafana" }}
     </mj-title>
     <mj-include path="./partials/layout/head.mjml" />
   </mj-head>

emails/templates/welcome_on_signup.txt

@@ -1,4 +1,4 @@
-[[Subject .Subject "Welcome to Grafana"]]
+[[HiddenSubject .Subject "Welcome to Grafana"]]
 
 Hi [[.Name]],