Refactor game authentication code to use ASP.NET JWT Authentication (#…

…1135)

Previously, the authentication code manually read the ID token and BaaS
JWKs and determined its validity using `JsonWebTokenHandler`. It then
threw an exception if the token was invalid, and relied on
`ExceptionHandlerMiddleware` to return the appropriate status code for
the game.

When I implemented JWT authentication for the website, I used the in-box
ASP.NET `AddJwtBearer` authentication and it greatly simplified matters.
I have been meaning to do the same for the game authentication code for
a while.

I got the final push I needed after #1129 which changed it so that every
expired token error was logged as an unhandled exception. This clutters
the logs and introduces misleading metrics in Grafana:


![image](https://github.com/user-attachments/assets/6045c18c-3fa0-401a-97a7-e7d5da3e508c)

As part of simplifying the authentication code, I have also removed the
legacy authentication flow, which the server used in its first weeks
being live before BaaS was established. This means we now have a hard
dependency on BaaS, but it is now open source and available for anyone
to host. This old authentication flow had not been tested in literal
years, so there's a good chance it wasn't functional anyway.

Aspire/Dawnshard.AppHost/appsettings.json

@@ -7,6 +7,5 @@
     }
   },
   "EnableStateManager": false,
-  "EnableWebsite": false,
-  "EnableGrafana": false
+  "EnableWebsite": false
 }

DragaliaAPI/DragaliaAPI.Database/ApiContext.cs

@@ -21,10 +21,6 @@ IPlayerIdentityService playerIdentityService
         this.playerIdentityService = playerIdentityService;
     }
 
-#pragma warning disable CS0618 // Type or member is obsolete
-    public DbSet<DbDeviceAccount> DeviceAccounts { get; set; } = null!;
-#pragma warning restore CS0618 // Type or member is obsolete
-
     public DbSet<DbPlayer> Players { get; set; } = null!;
 
     public DbSet<DbPlayerUserData> PlayerUserData { get; set; } = null!;

DragaliaAPI/DragaliaAPI.Database/DatabaseConfiguration.cs

@@ -38,9 +38,6 @@ IConfiguration config
                         .EnableDetailedErrors();
                 }
             )
-#pragma warning disable CS0618 // Type or member is obsolete
-            .AddScoped<IDeviceAccountRepository, DeviceAccountRepository>()
-#pragma warning restore CS0618 // Type or member is obsolete
             .AddScoped<IUserDataRepository, UserDataRepository>()
             .AddScoped<IUnitRepository, UnitRepository>()
             .AddScoped<IInventoryRepository, InventoryRepository>()