Add GCMParameterSpec to preloaded-classes

Needed for Bouncycastle 1.50 upgrade with art.

Change-Id: I901122c1ce21abba437a7537e70331724c3cbc9c
Add CertStoreParameters to preloaded-classes

For image creating, art needs this in the preloaded-classes list.
Otherwise it complains loudly about not being able to load it from a
class initializer in Provider.java.

Change-Id: Ie7ed5655cba038b504767c3de9f70b47a8965cce
Use BaseNetworkObserver in Tethering.

Tethering currently inherits from the AIDL interface
INetworkManagementEventObserver, so it has to provide no-op
implementations of all the interface's methods. Inherit from
BaseNetworkObserver and get rid of the no-ops.

[Cherry-pick of f4e90eac87bc31611ddd80c46fc924d35ce66c1c]

Bug: 9180552
Change-Id: I74859b0d77951005651aaaa418185857e40eeedb