Expose BroadcastOptions#setMaxManifestReceiverApiLevel as system API

Connectivity service is going to become a mainline module which
will not able to access hidden APIs. But it needs
BroadcastOptions#setMaxManifestReceiverApiLevel to restrict the
receiving of CONNECTIVITY_ACTION intent. Thus, expose it as a
system API to support the usage.

Bug: 170593746
Test: atest FrameworksNetTests
Test: atest CtsNetApi23TestCases
Test: atest KeyChainTests
Change-Id: Ic45552174c3f9e74141db4495bb99a582000b574
Merged-In: Ic45552174c3f9e74141db4495bb99a582000b574