avoid loading unnecessary problem data

[thecodingwizard]

We seem to be loading every problem's information in a number of places which would contribute to bigger bundle sizes.

• In the dashboard, where we load problem info for active problems / modules. We can move this to a vercel function
• In the USACO division table, where we also load a lot of problem info. We can load this only when needed.
• To migrate old problem ID's to new problem ID's. We can load this only when needed (or we can just not migrate old ID's anymore :P) I think, but I could be wrong, that we just no longer migrate old problem ID's
• Massive redirect files. We should use vercel to redirect this stuff
• Elsewhere? Not sure

[thecodingwizard]

As an extension, optimize user data by separating settings & activity into two documents to optimize data usage