Reimplement [read|write]ArraySet of Parcel inside NetworkCapabilities

Both of readArraySet and writeArraySet are hidden APIs inside
Parcel, so reimplement those two methods inside NetworkCapabilities
to prevent calling hidden APIs.

Bug: 170598012
Test: atest FrameworksNetTests
Change-Id: I70f75c1a0db92c6a5575c6a9917843d783dfaeea