instrumentation-base / configurator: support global configuration for all instrumentation

[ahayworth]

We want to allow the ability to provide configuration for all instrumentation in one pass; and to also support one instrumentation reading the configuration of another instrumentation. There are a few use-cases:

• This allows us to more easily support various combinations of c.use / c.use_all with either the -instrumentation-all gem or individually installed gems.
• We can more flexibly express dependencies between instrumentation (eg: between -rails and its sub-gems, or between something that uses Faraday and the -faraday instrumentation). Currently, we override user options when configuring inter-instrumentation dependencies.