Generic version of ConsumesAttribute

## Background and Motivation

This was mentioned in this issue but it looks like it didn't make it in. https://github.com/dotnet/aspnetcore/issues/37767

## Proposed API

```diff
namespace Microsoft.AspNetCore.Mvc;

+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
+public class ConsumesAttribute : ConsumesAttribute
+{
+ public ConsumesAttribute(string contentType) : base(typeof(T), contentType)
+ { }
+}
```

## Usage Examples

```csharp
[Consumes("application/x-www-form-urlencoded")]
[EndpointName(nameof(AddTodo))]
[Tags("TodoApi")]
async Task AddTodo(Todo todo, TodoDb db)
{
if (!MiniValidator.TryValidate(todo, out var errors))
return Results.ValidationProblem(errors);

db.Todos.Add(todo);
await db.SaveChangesAsync();

return Results.Created($"/todos/{todo.Id}", todo);
}
```

## Alternative Designs

## Risks

Start by reading the existing ConsumesAttribute API and the related discussion in issue 37767. Compare the proposed generic API and usage example with current conventions, then verify that the new public API builds and that its attribute usage behaves as shown.

Written by the indexing model from the issue text.