Add Support for Proxy Include Patterns for Agent Controller Communication

[jowerner]

The Master Controller can communicate with the Agent Controllers either directly or via an HTTPS proxy server. The configuration settings determine whether the direct route is taken or the proxy is used.

If a proxy is configured, all communication goes through the proxy by default. To bypass the proxy for certain hosts, we can configure a wildcard pattern. Currently, however, it is not possible to configure the other way around, i.e., to force the use of the proxy for certain hosts only.

Supporting both options would be beneficial because it is sometimes easier to express an include pattern for host names instead of an exclude pattern, or vice versa.