ClientProperties related updates

[abhipsaMisra]

This PR contains the following updates:

• Update

public class ClientProperties : ClientPropertyCollection {
    public ClientProperties();
    public ClientPropertyCollection Writable { get; private set; }
}

to

public class ClientProperties {
    public ClientProperties();
    public ClientPropertyCollection WritablePropertyRequests { get; private set; }
    public ClientPropertyCollection ReportedFromClient { get; private set; }
}

The reasoning here was 2 fold -
(1) The writable property update requests are usually the interesting bit in ClientProperties. But the previous design promoted the ReportedFropmClient properties to the top-level object. With this change in design, both the "reported" and "requested" properties are now present under their specific accessors.
(2) With everything being a dictionary for node, having the client reported properties under ClientProperties directly makes iterating through the collection difficult. Iterating ClientProperties directly would give you all client reported properties + the writable property requests under a Writable key. With this change in design, you can now iterate over ReportedFromClient and WritablePropertyRequests separately.

• Rename SubscribeToWritablePropertiesEventAsync to SubscribeToWritablePropertyUpdateRequestsAsync (this matches the WritablePropertyRequests in ClientProperties.)
• Remove "en-us" from URL links (I've not updated the non-pnp "en-us" links since it would better to update those in master instead).
• Rename the unit test package from Microsoft.Azure.Devices.Client.Tests to Microsoft.Azure.Devices.Client.Test

[owainc]

Any idea when this might be released in a preview?

[abhipsaMisra]

Hi @owainc , we are currently working to get a couple of other changes in before we put a release out, which we're targeting to have by the end of this month. Are you waiting for this specific change in particular?

[owainc]

@abhipsaMisra Not waiting for this specifically, could see it was a breaking change though (a good one) and wanted to get up to date :) End of the month sounds good.