vpat 43: add label to scaffold translator output (#4018)

In a new scaffold.ftl file.

Vpat 43 also indicates that the read-only state of the text field
does not get announced - it is a VoiceOver-specific issue on
Firefox, so it is not addressed here as it should be fixed
globally.

chrome/content/scaffold/scaffold.xhtml

@@ -51,6 +51,7 @@
 		<html:link rel="localization" href="browser/browserSets.ftl"/>
 		<html:link rel="localization" href="toolkit/global/textActions.ftl"/>
 		<html:link rel="localization" href="zotero.ftl" />
+		<html:link rel="localization" href="scaffold.ftl" />
 	</linkset>
 
 	<script>
@@ -535,7 +536,7 @@
 			</tabbox>
 			<splitter id="pane-splitter" resizeafter="farthest" />
 			<vbox id="right-pane">
-				<html:textarea id="output" readonly="true"/>
+				<html:textarea id="output" readonly="true" data-l10n-id="scaffold-translator-output"/>
 			</vbox>
 		</hbox>
 

chrome/locale/en-US/zotero/scaffold.ftl

@@ -0,0 +1,2 @@
+scaffold-translator-output =
+    .aria-label = Console

js-build/config.js

@@ -128,6 +128,7 @@ const scssFiles = [
 const ftlFileBaseNames = [
 	'zotero',
 	'preferences',
+	'scaffold',
 ];
 
 const buildsURL = 'https://zotero-download.s3.amazonaws.com/ci/';