MM-18818 Prompt admins to set the Support Email (#17296)

* MM-18818 Set default support to empty and handled the same in email templates

* #MM-18818 Admin advisor now warns for inconfigured support email address

* Updated text

* #MM-18818 gofmt'ed files

* #MM-18818 updated text and removed unused i18n strings:

* #MM-18818 updated i18n string ordering

* #MM-18818 Added test for support email advisory

* MM-18818 gofmt'd the file

* MM-18818 separated contextual notifications from configuration notifications in Admin Advisor

* #MM-18818 prevented support email with whitepsaces from being detected as filled

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

templates/partials/questions_footer.mjml

@@ -1,3 +1,4 @@
+<mj-raw>{{if .Props.SupportEmail}}</mj-raw>
 <mj-section padding="16px 0px 40px 0px">
   <mj-column>
     <mj-text css-class="footerTitle" padding="0px">
@@ -5,8 +6,9 @@
     </mj-text>
     <mj-text css-class="footerInfo" padding="0px">
       {{.Props.QuestionInfo}}
-      <a href='mailto:{{.Props.SupportEmail}}'>
+      <a href="mailto:{{.Props.SupportEmail}}">
       {{.Props.SupportEmail}}</a>
     </mj-text>
- </mj-column>
+  </mj-column>
 </mj-section>
+<mj-raw>{{end}}</mj-raw>