Improve platform TransitionSet behavior

1) Allow override values for a children of TransitionSet. For example for usages like this:
TransitionSet set = new TransitionSet().setDuration(300);
Fade fade = new Fade();
set.addTransition(fade);
fade.setDuration(100);
The result duration applied for fade transition is still 300. And it breaks all the flexibility of configuring sets.
The reason of it is clone() method which will be executed in beginDelayedTransition. And as part of clone() implementation of TransitionSet the children will be re-added to the new cloned set and set's duration will be re-applied again. To fix it I changed how we add transitions into set in clone().
2) Recently we had a bug about TransitionSet will crash during inflation if we provide duration for it via xml. I fixed similar issue for applying a path motion.

Test: added new tests for both issues
Change in AndroidX: aosp/803493
Bug: 64644617

Change-Id: If205845a83e29d49f8cced8a53d9f56a4ad740aa