Fix bug where folder items preview remain in low res state.

- We update the ranks of all folder items after loading, to ensure there are
  no gaps caused by removed folder items. This also ensures that we load
  the high resolution icons for all preview items.
- FolderIconPreviewVerifier#setFolderInfo was not always called
- Init mGridSize with [1, 1] to prevent divide by zero error in case
  setFolderInfo is not called

Bug: 126268196
Change-Id: I856489968665a39303e2922c78cf90f2b3ee6ebb