Cache PermissionInfos in whitelistAllSystemAppPermissions

PermissionInfo-s are not per package. Hence instead of resolving them
over and over again, cache already resolved PermissionInfo and reuse
them.

Before whitelistAllSystemAppPermissions took between 600 and 1100 ms on
a crosshatch-eng. Now it takes between 200-350 ms.

Test: Booted a few time and measured how long this method took
Bug: 139485700
Fixes: 136682954
Change-Id: I83221f9fb2ed00b67957a633d26906f4d8aeb26e