Commit Message: Add proxy proto transport socket
Additional Description: This is the part 1 PR described in #10682. It adds the transports socket / unit tests, a transport socket options struct for the proxy proto header, and does a refactor to make the listener filter use the common proxy proto constants (potentially want to move these now since the proxy proto config api type is not in extensions?)
Risk Level: Small
Testing: Unit
Docs Changes: None
Release Notes: None
Part Of: #1031
Signed-off-by: Weston Carlson <wez470@gmail.com>
Co-authored-by: Lizan Zhou <lizan@tetrate.io>
Mirrored from https://github.com/envoyproxy/envoy @ 8972b478e6c9f1e7342e3dbfb57b35317c0cc009
data-plane-api(Azure Pipelines)