Title: Opening this issue to track v2 support for protos in Q1.

Description: Opening this issue to track v2 support for following protos in Q1.
refer #12841 for details.

protos:
"//envoy/config/filter/thrift/router/v2alpha1:pkg",
"//envoy/config/health_checker/redis/v2:pkg",
"//envoy/config/resource_monitor/fixed_heap/v2alpha:pkg",
"//envoy/config/resource_monitor/injected_resource/v2alpha:pkg",
"//envoy/config/retry/omit_canary_hosts/v2:pkg",
"//envoy/config/retry/previous_hosts/v2:pkg",

Describe the issue.

[optional Relevant Links:]

see #12841 for details