Fix dash parser and more refactor

- Add new itags

exceptions/ContentNotAvailableException.java

@@ -0,0 +1,11 @@
+package org.schabi.newpipe.extractor.exceptions;
+
+public class ContentNotAvailableException extends ParsingException {
+    public ContentNotAvailableException(String message) {
+        super(message);
+    }
+
+    public ContentNotAvailableException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}