Idea: Use suggested streams

[flash1293]

Which streams to sync by default is a bit of a dilemma:

• Forcing the user to make a choice can be annoying on getting started - it's often a multi-step process (they need to check what streams are available, then guess which ones are relevant)
• However, when syncing all of them, it's possible for the initial sync to take a very long time if there are a lot of streams

As the Airbyte UI has the same issue, there is a middle ground now - suggested streams (distributed via metadata): https://github.com/airbytehq/airbyte/blob/5727127c7215e3da3a89863dcdcaf778787c7994/airbyte-integrations/connectors/source-github/metadata.yaml#L33

These are a curated default set that can be leveraged in airbyte-lib as well.