Add support for async requestCellInfoUpdate

-Add support for asynchronous CellInfo update requests.
-Return cached CellInfo for Q+ callers of
 getAllCellInfo().
-Naming cleanup to differentiate between
 getAllCellInfo() and requestCellInfoUpdate().

Bug: 37100068
Bug: 63737292
Bug: 26569588
Test: manual (via SL4A)
Change-Id: I85f063d54c314e38e1d9521847f5c2c079eb3aeb
1 file changed