[RAG] Embed workspace files

[anetaj]

• Workspace files are now embedded and saved to a vector store (if configured).
• The algorithm respects workspace ignored files (they won't be embedded).
• Files only get re-embedded if new or modified since the last embedding.
• For now, embedding only happens in the background when the extension is activated. You have to restart the extension after adding API keys.
• For now, only a few file types are supported. Unsupported files will be ignored.

Example docker-compose for OpenSearch:

# Reference:
#   https://opensearch.org/docs/latest/install-and-configure/install-opensearch/docker/#sample-docker-composeyml
version: "3"
services:
  opensearch:
    image: opensearchproject/opensearch:2.6.0
    container_name: opensearch
    environment:
      - cluster.name=opensearch
      - node.name=opensearch
      - discovery.type=single-node
      - bootstrap.memory_lock=true
      - "OPENSEARCH_JAVA_OPTS=-Xms512m -Xmx512m"
      - "DISABLE_INSTALL_DEMO_CONFIG=true"
      - "DISABLE_SECURITY_PLUGIN=true"
    ulimits:
      memlock:
        soft: -1
        hard: -1
    volumes:
      - opensearch_data:/usr/share/opensearch/data
    ports:
      - 9200:9200
      - 9600:9600
    networks:
      - opensearch
  opensearch-dashboards:
    image: opensearchproject/opensearch-dashboards:latest # Make sure the version of opensearch-dashboards matches the version of opensearch installed on other nodes
    container_name: opensearch-dashboards
    ports:
      - 5601:5601 # Map host port 5601 to container port 5601
    expose:
      - "5601" # Expose port 5601 for web access to OpenSearch Dashboards
    environment:
      OPENSEARCH_HOSTS: '["http://opensearch:9200"]' # Define the OpenSearch nodes that OpenSearch Dashboards will query
      DISABLE_SECURITY_DASHBOARDS_PLUGIN: "true" # disables security dashboards plugin in OpenSearch Dashboards
    networks:
      - opensearch
networks:
  opensearch:
volumes:
  opensearch_data: