Function app should return 405 for request on known route but unsupported HTTP method

I created a C# (isolated) function app with two HTTP-triggered functions. The `/products` path is defined like this:

```csharp
[Function("ProductsEndpoint")]
public async Task Run(
[HttpTrigger(AuthorizationLevel.Function, "get", "post", Route ="products")] HttpRequestData req)
{
```

If I send a DELETE request to this path:
```text
DELETE {{MdkRestServerless_HostAddress}}/api/products
```

the response is a `404 Not Found`:
```text
HTTP/1.1 404 Not Found
Content-Length: 0
Connection: close
Date: Thu, 02 May 2024 00:24:00 GMT
```

but the response _should_ be `405 Method Not Allowed` [[RFC 9110]], since the resource (`/products`) exists but just does not support the `DELETE` method.

[RFC 9110]: https://datatracker.ietf.org/doc/html/rfc9110#section-15.5.6

Start at the C# isolated function entry point `ProductsEndpoint.Run` and its `HttpTrigger` declaration for the `/products` route. Trace how a DELETE request is matched when only GET and POST are declared, then exercise the function app with supported and unsupported methods. Done means DELETE on the known route returns 405 instead of 404, while the existing methods continue to work.

Written by the indexing model from the issue text.