Use database connection instead of API

[hburn7]

Database refactor

• Closes Remove API dependency and use a direct database connection #68
• Closes Modify RatingAdjustment object #67
• Closes Remove historical global rank, country rank, and percentile tracking #66
• Closes Decay progressively instead of retroactively #63
• Closes Refactor for usage with new API structure #61
• Closes Refine algorithm #41

This is a substantial refactor of the processor. Instead of making an API connection, we now use a direct database connection. This substantially improves speed and reliability.

Additionally, the following changes have been made:

• Refactoring types to use new o!TR database types.
• Use the minimum amount of necessary fields in these types.
• Refactor all structs to use new types
• Refactor otr_model entirely (with help from @SourMongoose), utilizing the new algorithm @cytusine0 & @SourMongoose came up with.
• Improve quality in main.rs, each step of the processing pipeline is clearly outlined and documented.
• Remove global / country rank & percentile historical tracking. Should improve speeds substantially.