Add connectedservice input to push command

[gep13]

To allow usage of stored API Keys within the Organisation.

There is some conversation about this here:

https://twitter.com/jessehouwing/status/1066942111642193922

[gep13]

Should be possible by calling Get-VstsInput on the input, which should return a GUID, and then this GUID can be passed to Get-VstsEndPoint (https://github.com/Microsoft/azure-pipelines-task-lib/blob/master/powershell/Docs/Commands.md#get-vstsendpoint) to get all the required information.

[gep13]

What is being referred to here is the ability to use one of these inputs:

[gep13]

For the Chocolaty Task, this will likely mean adding a Radio Button input around the highlighted inputs here:

And also a new connectedService input. The user can then select from adding the source/apikey directly, or by selecting/adding an external feed.

NOTE This will only allow the usage of the ApiKey connection, as other connection types are not currently supported by Chocolatey.

@onovotny @devlead can I get your thoughts on this? Thanks

[gep13]

When testing this, the following was useful...

When doing Basis Authentication:

When doing External Azure DevOps Server:

When doing ApiKey:

Notice the difference in the Scheme of each one, and also the different parameters that are available.