[DO NOT MERGE] Wait for preloading images to complete before inflating notifications

 NotificationContentInflater waits on SysUiBg thread for images to load, with a timeout
 of 1000ms.

Test: 1. Build a test app that posts MessagingStyle notifications with a huge image (8k+) set as data Uri.
 2. SystemUi should not ANR
 3. adb logcat | grep NotificationInlineImageCache  - shows timeout/cancellation logs

Bug: 252766417
Bug: 223859644

(cherry picked from commit 195043f4)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:b9cd15ad8a2f87893164ad2ab518039bb0b61424)
Merged-In: I341db60223214cf2282b5c0270e343e1ce95fa01
Change-Id: I341db60223214cf2282b5c0270e343e1ce95fa01