Review dynamic components with serverless deployments

[Jeffail]

We're moving in a direction where feature toggles are primarily done by defining resources and swapping them out by pulling in different resource files with the -r flag. However, the serverless deployments work by embedding a single config within an environment variable, some thought needs to be made into whether we can support this pattern with lambdas.

We could expand the variables we parse to include an optional BENTHOS_RESOURCE_CONFIG which would include optional resources, where the feature toggled components would be defined.