Display search progress icon while loading the search results

Recording:
- With 2 second delay for resutls:
https://drive.google.com/file/d/1ljBprtEWa9RAHqglxH2YPrzsBRYDy8b5/view?usp=sharing
- With > 5 second delay for results:
https://drive.google.com/file/d/1dZ5erqXYiy2RozRF5L5l78IdKNf19vt2/view?usp=sharing

Bug: 361027422
Test: Manual
Flag: com.android.providers.media.flags.enable_photopicker_search

Change-Id: I58e68d7bd5ddffe0eadd27444e885ad619cf7386