Define upper-bound disk quotas for all apps.

Abusive or broken apps can go crazy and try allocating all of the
disk space on the device.  To mitigate the impact on system health,
set hard limits to block any given app from using more than 90% of
disk blocks, or 50% of disk inodes.

Also define the hard limit for AID_MEDIA_RW to avoid filling up the
device via the SD card.

Kick QUOTAON when scanning devices, since ext4 doesn't toggle
DQUOT_LIMITS_ENABLED during initial mount.

Test: cts-tradefed run commandAndExit cts-dev -m CtsAppSecurityHostTestCases -t android.appsecurity.cts.StorageHostTest
Test: cts-tradefed run commandAndExit cts-dev -m CtsOsTestCases -t android.os.cts.EnvironmentTest#testSaneInodes
Bug: 36450358
Change-Id: Iaa2bc6a2f0bc9047ee54c1d1a49bbda92142457a