Add a Builder to NetworkAgentConfig, and make it SystemApi.

Currently, only support the three elements in the config that are
known to be used.

Bug: 138306002
Test: builds, boots
Test: atest FrameworksTelephonyTests
Change-Id: I1d231ec2ddcff97c039bcbc815a39c1d3e26c410
3 files changed
tree: bbbbf2e5493b24eec662a86a7796fa033630db54
  1. core/
  2. services/
  3. tests/