Allow overriding AccessLogs at service-defaults level

#### Feature Description

Currently there is an AccessLogs configurable property at proxy-defaults, however this applies to all proxies on a consul cluster/environment, which is quite limiting. It would be helpful to have an AccessLogs property at service-defaults level, so it can be customized per-service, instead of globally (all or nothing).

#### Use Case(s)

The use-case would be being able to define specific enabling or disabling of AccessLogs, different log file paths, etc. per-service.

The issue does not name files, tests, or entry points; start by tracing the existing AccessLogs handling under proxy-defaults and how service-defaults are applied. Done means AccessLogs can be enabled, disabled, and configured with a distinct log path per service without changing the global proxy-defaults behavior.

Written by the indexing model from the issue text.