SDK updates from master branch.

This release is bringing changes from the master release 2021-05-13.
The previous preview release was based on the master release 2020-10-8.

Note: This preview release does not contain the device streaming feature. The device streaming feature is still available under previews/deviceStreaming, however, since there is no active development on-going for this feature, we're not including it as a part of our newer preview nugets.

Microsoft.Azure.Devices.Shared 1.29.0-preview-001

• Updates from GA release 2021-05-13.
• Add support for .NET 5.0 (#1900)
• Add native support for Azure IoT Plug and Play (PnP) APIs (#2005, #2014). For details on how these APIs differ from the existing device/module APIs, see this readme.

Microsoft.Azure.Devices.Client 1.38.0-preview-001

• Updated reference to Microsoft.Azure.Devices.Shared nuget.
• Updates from GA release 2021-05-13.
• Add support for .NET 5.0 (#1900)
• Add native support for Azure IoT Plug and Play (PnP) APIs (#2005, #2014). For details on how these APIs differ from the existing device/module APIs, see this readme.
• Add support for releasing unmanaged resources asynchronously. This is available on .NET Standard 2.1 and above. (#1977)

Microsoft.Azure.Devices 1.35.0-preview-001

• Updated reference to Microsoft.Azure.Devices.Shared nuget.
• Updates from GA release 2021-05-13.
• Make all clients mockable (#1875), (#1878), (#1881), (#1892)
• Add support for .NET 5.0 (#1900)

Microsoft.Azure.Devices.Provisioning.Client 1.18.0-preview-001

• Updated reference to Microsoft.Azure.Devices.Shared nuget.
• Updates from GA release 2021-05-13.
• Add support for .NET 5.0 (#1900)

Microsoft.Azure.Devices.Provisioning.Transport.Mqtt 1.16.0-preview-001

• Updated reference to Microsoft.Azure.Devices.Shared nuget.
• Updates from GA release 2021-05-13.
• Add support for .NET 5.0 (#1900)

Microsoft.Azure.Devices.Provisioning.Transport.Amqp 1.15.0-preview-001

• Updated reference to Microsoft.Azure.Devices.Shared nuget.
• Updates from GA release 2021-05-13.
• Add support for .NET 5.0 (#1900)

Microsoft.Azure.Devices.Provisioning.Client.Transport.Http 1.14.0-preview-001

• Updated reference to Microsoft.Azure.Devices.Shared nuget.
• Updates from GA release 2021-05-13.
• Add support for .NET 5.0 (#1900)

Microsoft.Azure.Devices.Provisioning.Security.Tpm 1.14.0-preview-001

• Updated reference to Microsoft.Azure.Devices.Shared nuget.
• Updates from GA release 2021-05-13.
• Add support for .NET 5.0 (#1900)

Microsoft.Azure.Devices.Provisioning.Service 1.18.0-preview-001

• Updated reference to Microsoft.Azure.Devices.Shared nuget.
• Updates from GA release 2021-05-13.
• Add support for .NET 5.0 (#1900)