Migrate scores to use proper relationships

[Slendy]

The old way scores worked was using players' usernames in a comma-delimited list which has obvious problems like being able to spoof scores because the system ultimately trusts the score uploader. Other problems include different permutations of usernames will create entirely new scores instead of updating old ones.

The migration uses raw SQL because after the migration the entity is no longer compatible and would be complicated to implement with EF as it is now. There is a new feature in NET 8.0 to map raw SQL queries to objects but it doesn't release until November of this year.

Some drawbacks of the new system are that non-existent users are no longer allowed to keep scores. This also means that once a user is deleted, all of their scores will also be deleted. In some cases this is beneficial; for example, if a single user cheated many scores you can remove all of their scores by simply deleting their account.

Since this PR also creates more scores per level since every user gets their own score regardless of the number of players that were in the session, there also needs to be a rework of the score viewer on the website to have pagination and filter by score type but that's outside the scope of this PR.

TODO

• Test migration more (maybe write unit tests)
• Test in-game uploading and reading of scores in different games
• Change website leaderboard to handle ties like the games (implemented in Refactor profile and slot pages to use iFrames for pagination #839)

In some cases where people have multiple scores under the same level and category will have their highest score selected and kept.

[sudokoko]

LGTM, just a few nitpicks and questions

[Zaprit]

Looks good, see my question in the comment though

[sudokoko]

Decided to take another look at this since there have been changes since I approved a month ago. Still looks good.