Refactor events and DB

[avichalp]

This PR achieves the following:

• Moves the SQL queries from code into separate .sql files and use prepared queries.
• Moves config such as contract addresses and db path into a separate config.toml
• Adds a subscribe method that runs in a loop in the background to poll on the getLogs endpoint to fetch new events (todo: move to websocket connection in future).
• Refactor some exiting Indexing code.
• Adds a unit test for parsing Register events (todo: needs to add more tests later)

[haardikk21]

sorry i'm not familiar with sqlx, but what are these json files and are they ok to be committed?

[avichalp]

sqlx uses these JSON files for compile time SQL checks without needing an active database connection. For instance, if you change a SQL query that is being used, but your new query has a wrong column name it will be caught at the compile time.

To include a new .sqlx file for a new query, you would run sqlx prepare (I have included a command in Makefile for this.)

I think it would be helpful if we commit these files. Otherwise, if you want this kind of check at dev time, you must generate these files every time.

[avichalp]

here is a nice explanation of what this is doing from the readme

[haardikk21]

awesome, ty!

[haardikk21]

🔥 - thank you for setting this up

[haardikk21]

(i meant the config file)

[haardikk21]

ah, we're getting there 😆