Add a systemapi constructor for NetworkAgent

Bug: 138306002
Bug: 139268426
Test: atest FrameworksNetTests FrameworksWifiTests FrameworksTelephonyTests
      make doc-comment-check-docs
Change-Id: I288ea32fac07a9a486e2ea451a2c9b098446a74c
2 files changed
tree: 8adea30d604973862bfe3545ecc13af955c79c5b
  1. core/
  2. services/
  3. tests/