[Tracking] C#/Utilities: resolve TODOs

[TheArcaneBrony]

Generated at commit 57827bc9:

• extra/admin-api/Utilities/Spacebar.Cdn.Migration/FsckService.cs:174: // TODO: not implemented?
• extra/admin-api/Utilities/Spacebar.Cdn.Migration/FsckService.cs:180: // Path = $"/app-icons/{x.Id}/{x.OwnerId}", // TODO - no db property for splash?
• extra/admin-api/Utilities/Spacebar.AdminApi.TestClient/Classes/OpenAPI/OpenAPISchema.cs:307: case "additionalProperties": //TODO