Add an API hint for metered multipath traffic.

This allows an application that knows how to provide seamless
network connectivity (e.g., using QUIC multipath) to find out if
doing so is desired.

(cherry picked from commit 231efb08b7cbbc1790261b67fbac8b3fb94bb778)

Test: builds, boots, runtest frameworks-net passes.
Bug: 34630278
Change-Id: Ic7fd0b9e1cd879fdfaf84009d7125391895e9087
5 files changed
tree: 4c5bbd4f99683660a33eb35da8cccd17e3870c2d
  1. core/
  2. services/
  3. tests/