Port Bug #64647 --> "Paste without Formatting" (plain text) on context menus and edit menu (e-mail & composer)

mail/components/compose/content/MsgComposeCommands.js

@@ -593,6 +593,7 @@ function updateComposeItems() {
 }
 
 function updateEditItems() {
+  goUpdateCommand("cmd_pasteNoFormatting");
   goUpdateCommand("cmd_pasteQuote");
   goUpdateCommand("cmd_delete");
   goUpdateCommand("cmd_selectAll");

mail/components/compose/content/messengercompose.xul

@@ -195,6 +195,7 @@
   <menuitem label="&cut.label;" accesskey="&cut.accesskey;" command="cmd_cut"/>
   <menuitem label="&copy.label;" accesskey="&copy.accesskey;" command="cmd_copy"/>
   <menuitem label="&paste.label;" accesskey="&paste.accesskey;" command="cmd_paste"/>
+  <menuitem command="cmd_pasteNoFormatting"/>
   <menuitem label="&pasteQuote.label;" accesskey="&pasteQuote.accesskey;" command="cmd_pasteQuote"/>
   <menuitem label="&delete.label;" accesskey="&delete.accesskey;" command="cmd_delete"/>
   <menuseparator/>
@@ -267,7 +268,8 @@
           <menuseparator/>
           <menuitem id="menu_cut" label="&cutCmd.label;" key="key_cut" accesskey="&cutCmd.accesskey;" command="cmd_cut"/>
           <menuitem id="menu_copy" label="&copyCmd.label;" key="key_copy" accesskey="&copyCmd.accesskey;" command="cmd_copy"/>
-          <menuitem id="menu_paste" label="&pasteCmd.label;" key="key_paste" accesskey="&pasteCmd.accesskey;" command="cmd_paste"/>
+          <menuitem id="menu_paste" label="&pasteCmd.label;" key="key_paste" accesskey="&pasteCmd.accesskey;" command="cmd_paste"/>
+          <menuitem id="menu_pasteNoFormatting" command="cmd_pasteNoFormatting"/>
           <menuitem id="menu_pasteQuote"/>
           <menuitem label="&editRewrapCmd.label;" accesskey="&editRewrapCmd.accesskey;" command="cmd_rewrap"/>
           <menuitem id="menu_delete" label="&deleteCmd.label;" key="key_delete" accesskey="&deleteCmd.accesskey;" command="cmd_delete"/>