Use `pittgoogle-client` instead of `pgb-broker-utils`

[troyraen]

Update all necessary code/files to remove the pgb-broker-utils python package, and instead use tools from pittgoogle-client.

mwvgroup/pittgoogle-client#6 is a PR containing a major refactor of pittgoogle-client, so this likely needs to wait until that is done. After that happens, we'll need to check and see which functions/classes still need to be added to pittgoogle-client for this to work (and then add them).

[wmwv]

https://github.com/mwvgroup/pittgoogle-client/pull/6 has been merged. What's the next step for this current Issue?

[troyraen]

Thanks, we need to evaluate what still needs to be added to pittgoogle-client. Below is my rundown from looking at the imports in classifier/main.py. Perhaps I can spend a little time this weekend to knock out the simpler ones. @wmwv if there are particular items that would be helpful to prioritize for #13, let me know.

from broker_utils import data_utils, gcp_utils, math

This is using:

• [ ] broker_utils.data_utils.alert_dict_to_dataframe, which should be easy to port over
• [ ] broker_utils.gcp_utils.insert_rows_bigquery, which is easy to port over -- but, 1) the call to get_table causes problems at high alert rates (see https://github.com/mwvgroup/Pitt-Google-Broker/issues/96#issuecomment-983282727) and should be dropped; and 2) we should just ditch this call altogether and use a BigQuery subscription instead.
• [ ] broker_utils.gcp_utils.publish_pubsub. I know where/how I want to add this to pittgoogle-client and should just do it.
• [ ] broker_utils.math is being import but not used, so I didn't look at it further.

from broker_utils.types import AlertIds

• [ ] AlertIds is awkward and clunky to use and I want to drop it. The new pittgoogle-client has an Alert class and I can look at making the IDs easily accessible from there. In the meantime, the IDs can just be pulled directly from the alert.

from broker_utils.schema_maps import load_schema_map, get_value

• [ ] For now, we should probably just port broker_utils.schema_maps over. Longer term, I'll need to spend a little more time thinking this through. The way that schema maps are currently implemented is a pain and I don't have a clear solution right now.

from broker_utils.data_utils import open_alert

• [ ] broker_utils.data_utils.open_alert is a very convenient function that accepts alerts in many different forms and hides a big ol' mess underneath. I think I can do a much cleaner implementation using class methods on pittgoogle.pubsub.Alert (e.g., Alert.from_cloud_run, Alert.from_cloud_functions, Alert.from_path, etc.).

[troyraen]

The way that schema maps are currently implemented is a pain and I don't have a clear solution right now.

Jotting down some thoughts: This should probably be handled by pittgoogle.pubsub.Alert without the user having to do anything except specify which survey the alert is coming from (and possibly the schema version). The schema maps should be packaged with the pittgoogle-client so that they don't have to be supplied or retrieved from somewhere else.

[troyraen]

I've started working on this, but realized that simply porting these functions over is really not the way to go. Most of this should be handled by the pittgoogle.pubsub.Alert class, so I'm implementing new methods there.