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 48a2a32bdd59b2b1878f1eb67b978ec20745024f)

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