Add authoring guide, stack adapters, and CI layer distinction

- AUTHORING.md: instructions for teams writing requirements + tests
- Stack adapters: java.patterns, python.patterns, go.patterns
- Quality checklist for new requirements
- Open question on adapter threshold for minor stacks

.tests/adapters/python.patterns

@@ -0,0 +1,4 @@
+cloud_sdk_imports=import boto3|from google\.cloud|from azure\.
+jwt_libraries=import jwt|from jose|from authlib
+auth_endpoints=@app\.route.*/login|@app\.post.*/authenticate|def login\(
+external_url=https?://(?!localhost|127\.0\.0\.1|10\.|192\.168\.)(?!.*reltio\.(com|net|io))