Add Support for Additional Response Content-Types

[alzimmermsft]

Currently, Azure Core expects that the Content-Type of a response is either json or xml. There are additional Content-Types that need to be supported such as plain text, images, and additional forms of json or xml that aren't currently supported.

[alzimmermsft]

Azure Search uses text/plain

[lmazuel]

AppConfig could use application/vnd.microsoft.appconfig.kv.v1+json if that helps

[lmazuel]

If that could helps, some notes on what Python is doing:

• When you call the pipeline, you pass a parameter to say if you want the pipeline to "pre-deserialize" the body (stream=True/False):
  • If you pass stream=True, pipeline doesn't touch the body and give you back an open socket on the HTTP connection (e.g. download blob). Content-Type is ignored.
  • If you do pass stream=False, this means load the body in memory, and use the Content-Type to do a first pass:
    • If regexp match JSON, create the JSON object
    • Else if XML, create a XML tree
    • Else if text/*, decode the body and return the string
    • Else fail for content-type impossible to handle

[weidongxu-microsoft]

mgmt-plane got response as application/json 99.9%.

automation has a text/powershell.
https://github.com/Azure/azure-rest-api-specs/blob/master/specification/automation/resource-manager/Microsoft.Automation/stable/2018-06-30/runbook.json#L54-L91

I think at present modelerfour will parse this as binary, so we are still safe.

[alzimmermsft]

This issue may be broken out into smaller children issues per Content-Type needing support.