[mainline] Expose getTetherApnRequired API as system API

1. getTetherApnRequired API rename to isTetherApnRequired.
2. Expose isTetherApnRequired API as system API.

Bug: 142365448
Test: Build pass.
      atest TetheringConfigurationTest (PASS)

Change-Id: Iafb2e4fbddb0251e23673742d990ad098a8ae375
Merged-In: Iafb2e4fbddb0251e23673742d990ad098a8ae375
2 files changed
tree: b577f67ceb7bd9884f654b73149d0ea43650e2e9
  1. Tethering/