estuary-cdk: support for initially disabled bindings

[williamhbaker]

ATF supports a concept of "selected streams", which will be enabled by defualt, and the rest of the discovered streams will be disabled by default. For example, source-salesforce uses this: https://github.com/estuary/airbyte/blob/master/airbyte-integrations/connectors/source-salesforce/selected_streams.json

The idea is that if a connector can discover hundreds and hundreds of streams but there's only a small set of those that users usually care about, its best not to capture and create collections for all of them, as this can cause downstream issues like limits on how many bindings a single materialization can have.