Adding API for refreshing the state of an AccessibilityNodeInfo.

Sometimes a client needs to hold onto an accessibility node info and
this info may get into a stale state. The clent has to be able to
request a refresh of the info. This change adds a refresh call to
AccessibilityNodeInfo.

bug:6711796

Change-Id: I580a9a5d9fd1f705ea0a2cf4d3ff65543714c9c3