Http Requests with Transfer-Encoding: chunked report an empty body

Sending requests to a Java HttpTriggered function results in an empty body if transfer-encoding is set to chunked

#### Investigative information

Please provide the following:

- Timestamp: local
- Function App name: HttpTriggerJava
- Function name(s) (as appropriate): -
- Invocation ID: -
- Region: -

#### Repro steps

Provide the steps required to reproduce the problem:

1. Send a http request which does not contain content-length but uses a transfer-encoding: chunked style of sending data
2. The function app fails to read the request body

#### Expected behavior
transfer-encoding: chunked works as expected

#### Actual behavior

The request body is empty

#### Known workarounds

provide the content-length client side by reading the entire request into memory. Not viable as a proxy service where we ourselves get chunked requests.

#### Related information

Provide any related information

* Programming language used: Java & C# as a POC to call with the correct headers

```java
package org.example.functions;

import java.io.InputStream;
import java.util.*;
import java.util.stream.Stream;

import com.microsoft.azure.functions.annotation.*;
import com.microsoft.azure.functions.*;

/**
* Azure Functions with HTTP Trigger.
*/
public class HttpTriggerJava {
/**
* This function listens at endpoint "/api/HttpTriggerJava". Two ways to invoke it using "curl" command in bash:
* 1. curl -d "HTTP Body" {your host}/api/HttpTriggerJava
* 2. curl {your host}/api/HttpTriggerJava?name=HTTP%20Query
*/
@FunctionName("HttpTriggerJava")
public HttpResponseMessage run(
@HttpTrigger(name = "req", methods = {HttpMethod.POST},
authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage> request,
final ExecutionContext context) throws Exception {
context.getLogger().info("Java HTTP trigger processed a request.");
//
return request.createResponseBuilder(HttpStatus.OK).body("Hello").build();
}
}

```

```csharp
using System;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using System.Threading;
using System.Net.Http;
using System.Net;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;

namespace FunctionApp1
{
public class Function1
{
[Function("Function1")]
public async Task GeneratePdfAsync(
[HttpTrigger(AuthorizationLevel.Function, "post", Route = "documents/{tenant}/{engine}/{template}")] HttpRequestData req,
string engine,
string tenant,
string template,
CancellationToken ct)
{
using var client = new HttpClient() { BaseAddress = new Uri("http://localhost:50251/api/HttpTriggerJava") };

using var request = new HttpRequestMessage()
{
Method = HttpMethod.Post
};

//request.Content = new StringContent(await (new StreamReader(pdfRequest.Payload)).ReadToEndAsync());
request.Content = new StreamContent(req.Body);
request.Content.Headers.Add("Content-Type", "application/octet-stream");
using var response = await client.SendAsync(request, ct);
if (response.StatusCode == HttpStatusCode.OK)
return new FileStreamResult(await response.Content.ReadAsStreamAsync(ct), "application/pdf");
else
return new BadRequestObjectResult(await response.Content.ReadAsStringAsync());
}
}
}
```