Update Unity2020.3.38f1 MRTK 2.8.2 and latest qr nuget and add missing files etc

[chgatla-microsoft]

Description

Name of sample: (example: ResizeAppView, or proposed name of new sample)

Testing

Type of change

• [ ] Bug fix
• [ ] New feature
• [ ] Porting to new language

Supported platforms

Minimum OS version: (example: 18362)

• [ ] All UWP platforms
• [ ] Desktop
• [ ] Holographic
• [ ] IoT
• [ ] Xbox
• [ ] 10X

Supported languages

• [ ] C#
• [ ] C++/WinRT

Additional remarks