LogAccessDialogActivity improvements

1. Makes the activity under AlertDialog translucent

When the AlertDialog is dismissed, a dialog like view can be seen with
the activity's label (with a "%s" placeholder) can be seen.
This change makes the activity itself translucent.

2. Handles cancel/dismiss of the dialog

When the dialog is canceled (eg. pressing back button or tapping
outside the dialog) decline the log access request.
When the dialog is dismissed finish the activity hosting the dialog.

3. Clean up unused code, some refactoring, more error handling

Bug: 228001277
Bug: 228563090
Test: Manual
Change-Id: Ib5f39eb12b41ed4137bc281b12e30072c9f5b7c7