Bug 1699207 - Use the same accesskey to toggle Troubleshoot Mode on and off. r=mkmelin

Using M as the same Troubleshoot Mode accesskey key for on and off.
Also updated the menubar items to be consistent.
We don't need to update the fluent strings since we're only changing accesskeys for the English version, so this won't affect translators.

Differential Revision: https://phabricator.services.mozilla.com/D156990

--HG--
extra : amend_source : cf647646e96c090260ad7ffb8411c4cb0a22dec3

mail/locales/en-US/messenger/appmenu.ftl

@@ -172,44 +172,44 @@ appmenu-tools-dev-tools =
 ## Help
 
 appmenu-help-panel-title =
-    .title = Help
+  .title = Help
 
 appmenu-help-get-help =
-    .label = Get Help
-    .accesskey = H
+  .label = Get Help
+  .accesskey = H
 
 appmenu-help-explore-features =
-    .label = Explore Features
-    .accesskey = F
+  .label = Explore Features
+  .accesskey = F
 
 appmenu-help-shortcuts =
-    .label = Keyboard Shortcuts
-    .accesskey = K
+  .label = Keyboard Shortcuts
+  .accesskey = K
 
 appmenu-help-get-involved =
-    .label = Get Involved
-    .accesskey = G
+  .label = Get Involved
+  .accesskey = G
 
 appmenu-help-donation =
-    .label = Make a Donation
-    .accesskey = D
+  .label = Make a Donation
+  .accesskey = D
 
 appmenu-help-share-feedback =
-    .label = Share Ideas and Feedback
-    .accesskey = S
+  .label = Share Ideas and Feedback
+  .accesskey = S
 
 appmenu-help-enter-troubleshoot-mode2 =
-    .label = Troubleshoot Mode…
-    .accesskey = M
+  .label = Troubleshoot Mode…
+  .accesskey = M
 
 appmenu-help-exit-troubleshoot-mode2 =
-    .label = Turn Troubleshoot Mode Off
-    .accesskey = O
+  .label = Turn Troubleshoot Mode Off
+  .accesskey = M
 
 appmenu-help-troubleshooting-info =
-    .label = Troubleshooting Information
-    .accesskey = T
+  .label = Troubleshooting Information
+  .accesskey = T
 
 appmenu-help-about-product =
-    .label = About { -brand-short-name }
-    .accesskey = A
+  .label = About { -brand-short-name }
+  .accesskey = A

mail/locales/en-US/messenger/menubar.ftl

@@ -48,15 +48,15 @@ menu-help-share-feedback =
 
 menu-help-enter-troubleshoot-mode =
     .label = Troubleshoot Mode…
-    .accesskey = T
+    .accesskey = M
 
 menu-help-exit-troubleshoot-mode =
     .label = Turn Troubleshoot Mode Off
-    .accesskey = O
+    .accesskey = M
 
 menu-help-troubleshooting-info =
     .label = Troubleshooting Information
-    .accesskey = I
+    .accesskey = T
 
 menu-help-about-product =
     .label = About { -brand-short-name }