[Config] Support Dynamic Sampling

[jackshirazi]

Changing sampling can be done dynamically and may be a useful mechanism to "turn off" part of the agent - but doesn't turn off metrics or log sending. There is an existing implementation of a dynamically adaptable sampler at
https://github.com/open-telemetry/opentelemetry-java/blob/main/sdk-extensions/jaeger-remote-sampler/src/main/java/io/opentelemetry/sdk/extension/trace/jaeger/sampler/JaegerRemoteSampler.java