Sync price feed

[harisang]

This PR adds a simple job that pushes all prices collected in the prices table of the analytics db to Dune. It mimics PR #103, and is meant to run as a cronjob. I followed the "legacy method" as there are some concerns about the current way Prefect has been integrated in this repo.

I also prepared this PR in the infra repo. https://github.com/cowprotocol/infrastructure/pull/2217

Note: there are currently not any tests. I saw there are some tests for the app-data sync, so i could try to basically copy-paste those, as i am not sure what's the best way to test this

[fhenneke]

Code looks reasonable.

If you do not intend to add tests in this PR, please add an issue and add tests later. We need to test stuff like this.

[harisang]

Code looks reasonable.

If you do not intend to add tests in this PR, please add an issue and add tests later. We need to test stuff like this.

How would a test look like though?

As a sanity check, one can set

PRICE_FEED_TARGET_TABLE = "test_price_feed_ethereum"
DUNE_API_REQUEST_TIMEOUT = 600

run

python -m src.main --sync-table price_feed

and confirm the table on dune is being updated.

But i am not sure what a test would check, except for basically running the above command and syncing into some test table.