Adds handle to NanoAppInstanceInfo Parcel

- Since mHandle (UID) was not recorded in writeToParcel, it always
returned 0 as the UID. This resulted in error messages claiming
mismatches between the reported and actual UID of nanoapps when called
from an external process.
- Also fixes the Parcel constructor to actually read the mContexthubId
field.

Bug: 37785458
Test: Compile and load, verify error message doesn't appear
Change-Id: I2ff75f510aae549c741786f5746862256ea5a877