udp_proxy: support proxy access logging

[giantcroc]

Signed-off-by: giantcroc [email protected]

Commit Message: Some stats like no_route and idle_timeout can't be printed by session access log, so we need proxy-level access logging to log global stats. Additional Description: Risk Level: Low Testing: Docs Changes: Release Notes: Platform Specific Features: [Optional Runtime guard:] [Optional Fixes #Issue] [Optional Fixes commit #PR or SHA] [Optional Deprecated:] [Optional API Considerations:]

[repokitteh-read-only[bot]]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy/|docs/root/api-docs/). envoyproxy/api-shepherds assignee is @markdroth CC @envoyproxy/api-watchers: FYI only for changes made to (api/envoy/|docs/root/api-docs/).

:cat:

Caused by: https://github.com/envoyproxy/envoy/pull/23218 was opened by giantcroc.

see: more, trace.

[repokitteh-read-only[bot]]

CC @envoyproxy/dependency-shepherds: Your approval is needed for changes made to (bazel/.*repos.*\.bzl)|(bazel/dependency_imports\.bzl)|(api/bazel/.*\.bzl)|(.*/requirements\.txt)|(.*\.patch). envoyproxy/dependency-shepherds assignee is @mattklein123

:cat:

Caused by: https://github.com/envoyproxy/envoy/pull/23218 was synchronize by giantcroc.

see: more, trace.

[giantcroc]

Sorry, misoperation, change to another PR.