Use an external json schema for botconfig

[isuruf]

cc @ytausch @beckermr

[isuruf]

We'll move the Pydantic model to regro/cf-scripts and dump the schema to that repo too. Then we can use the URL for that file here.

[ytausch]

Some thoughts about this:

• Do we really need Url and orjson here? I think it should be enough to reference the other schema as a string, removing the additional serialization overhead.
• I suggest not to include the other schema as JSON schema but rather to properly import it as a Pydantic model. Otherwise, it will not be possible to use the Pydantic model to access all fields, as explained here. I don't like seeing Pydantic to be downgraded to a JSON schema generation engine, as it's much more powerful if used correctly.