Fixed local cdc docker compose setup to use custom embeddings and configured a local data path

[dwnoble]

Fixes when running ./run_cdc_dev_docker.sh :

• Updated FLASK_ENV from local to custom to show the custom_dc homepage
• Added IS_CUSTOM_DC true to load only custom dc embeddings
• Added OUTPUT_DIR to env configuration, which:
  • Loads the custom topic cache in dc-website
  • Configures the ADDITIONAL_CATALOG_PATH (custom_catalog.yaml) which contains custom dc embeddings and index definitions
  • Mounts local sqlite database for the dc-mixer