Backport of Inline API Gateway TLS cert code into release/1.15.x#16306

andrewstucki merged 3 commits intorelease/1.15.xhashicorp/consul:release/1.15.xfrom

backport/api-gateway-inline/gratefully-current-terrierhashicorp/consul:backport/api-gateway-inline/gratefully-current-terrierCopy head branch name to clipboard