clean up protocol definition files & change to yamlschema

[jrhizor]

• convert to json for consistency
• make the names of the files match the exact title of the schema
• change the invalid reference "$ref": airbyte_schema.yaml#/definitions/AirbyteStream to a valid "$ref": #/definitions/AirbyteStream

[michel-tricot]

I left it to be yaml for readability purposes but I am ok moving back to Json.

[michel-tricot]

You need to change gradle to not expect yamlschema

[jrhizor]

I removed repetition of the file name in self-references across all of the types and switched everything to use yaml. I also cleaned up paths that were confusing when scoped with "json".

[jrhizor]

Interesting gotcha: the folder for singer_types can't be named types since it'll get clobbered by the other resources/types.