[performance] convert enum strings to ints

[NyaaaWhatsUpDoc]

Description

This helps improve performance by reducing the amount that these enums take-up in disk-space in their respective tables, and improves performance (however minorly) by reducing memory impact of models requiring only int enums instead of strings and also simplifying the comparisons between values of these types.

However, on larger databases this will likely be a monstrously large migration given the nature of it and it acting on the largest table we have, statuses :')

Checklist

• [x] I/we have read the GoToSocial contribution guidelines.
• [x] I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
• [x] I/we have not leveraged AI to create the proposed changes.
• [x] I/we have performed a self-review of added code.
• [x] I/we have written code that is legible and maintainable by others.
• [x] I/we have commented the added code, particularly in hard-to-understand areas.
• [ ] I/we have made any necessary changes to documentation.
• [ ] I/we have added tests that cover new code.
• [x] I/we have run tests and they pass locally with the changes.
• [x] I/we have run go fmt ./... and golangci-lint run.

[tsmethurst]

Looking good!