ANDROID: Initial commit of Incremental FS

Fully working incremental fs filesystem

[CPNOTE: 20/07/21] Lee: Asked Paul to open an OoT bug to follow progress

Bug: 133435829
Signed-off-by: Eugene Zemtsov <ezemtsov@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
[Lee: Squashed all subsequent changes into this initial patch]
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Change-Id: I02cce0b654d0ef74de0a190d30907410b23ab160
Signed-off-by: Lee Jones <joneslee@google.com>