Improve performance of FreeIPA's JSON serializer and deserializer. * Don't indent and sort keys. Both options trigger a slow path in Python's json package. Without indention and sorting, encoding mostly happens in optimized C code. * Replace O(n) type checks with O(1) type lookup and eliminate the use of isinstance(). * Check each client capability only once for every conversion. * Use decoder's obj_hook feature to traverse the object tree once and to eliminate calls to isinstance(). Closes: https://fedorahosted.org/freeipa/ticket/6655 Signed-off-by: Christian Heimes <cheimes@redhat.com> Reviewed-By: Martin Basti <mbasti@redhat.com> Reviewed-By: Jan Cholasta <jcholast@redhat.com>