Add missing commonDialog.js from dictionary manager

Currently provides close-on-Esc functionality

chrome/content/zotero/commonDialog.js

@@ -0,0 +1,14 @@
+window.addEventListener('keypress', function (event) {
+	if (event.key == 'Escape') {
+		try {
+			let elem = document.querySelector('button[dlgtype="cancel"]');
+			if (!elem) {
+				elem = document.getElementById('cancel-button');
+			}
+			elem.click();
+		}
+		catch (e) {
+			window.close();
+		}
+	}
+});