Add rudimentary JavaScript highlighting to query text view

MongoView/Synax Highlighting/JavaScriptHighlighter.swift

@@ -231,9 +231,12 @@ class JavaScriptHighlighter {
     }
     
     private func consumeObjectKey() {
+        guard let char = peek() else { return }
         let keyStart = currentIndex!
-        while let char = peek(), identifiers.contains(char) {
-            consume()
+        if identifierStarts.contains(char) {
+            consumeIdentifier()
+        } else if char == "'" || char == "\"" {
+            consumeString()
         }
         print("Object key: '\(text[keyStart..<currentIndex])'")
     }