Service Discovery: Per-method call and cache timeouts

[bronsh]

Problem: There might be a need to change cache TTLs for specific methods in deployed services (e.g. production) via configuration, or to disable them outright. After modifying the Caching proxy to support TTL per method, there isn't any way to configure it.

Problem: Similarly, devs want to be able to define individual timeouts per service method. For example, methods that rely on DB will be allowed longer timeouts.

Proposed solution: Add a new configuration that allows changing both the request and caching TTLs and disabling the caching for any specific method. This configuration should reside close to service discovery configuration. This implies we could define per-client TTLs.