Add Ingestion for Cosmos Docs

Need to ingest Cosmos Docs
The website is really small (less than 50 pages of content), expecting minimum to no disruption to existing retrieval quality.

airflow/dags/ingestion/ask-astro-load-cosmos-docs.py: incremental ingestion that runs periodically
airflow/dags/ingestion/ask-astro-load.py: added extract and ingest cosmos docs in bulk load
airflow/include/tasks/extract/cosmos_docs.py: main file that handles the extraction from cosmos website
- Note: only the main body of each page is extracted to minimize noise so the parsing logic is written tailoring to this data source (e.g. looking for article tag in the html body)

This is what the dataframe looks like after extracting (very small website not a lot of content overall) df_dump.csv
Airflow Ingestion UI confirmation that it is working for bulk load
Incremental ingestion works successfully on Airflow UI

Existing questions have no quality degradation
New questions specific to cosmos are correctly answered (see csv below, note: ordering of the references in this csv is not the same as actual result) cosmos_ingest_1.csv

closes #277

Latest commit:	`1b8037f`
Status:	✅ Deploy successful!
Preview URL:	https://6d425522.ask-astro.pages.dev
Branch Preview URL:	https://ingest-cosmos-docs.ask-astro.pages.dev

astronomer / ask-astro