Clarify UDP encapsulation socket API

This change updates the getSocket() methods for IPsec to improve clarity
of the return types, both for public APIs, and internal-only methods.

Bug: 72473753
Test: APIs updated, CTS + unit tests ran.
Change-Id: I0afebd432c5d04c47c93daa1ce616d712aa323d7
1 file changed
tree: f8ab439f911727a0d7813accf11c6905c5e5b711
  1. core/
  2. services/
  3. tests/