Replace Docker Hub references with GitHub references

[MichaelSimons]

Fixes #1176

This PR contains the following changes:

1. Replaced the Docker Hub references with Github except for in the Docker Hub readmes and a few select links that specific to Docker Hub (e.g. the official docker hub images).
2. Updated the Windows base image license to be identical to dotnet-docker. This was necessary as the template logic was calling into the URL formatting template and special casing this would have been difficult.
3. Updated the supported-tags documentation to be more like dotnet-docker in a few areas as a way to eliminate docker hub links.
4. Removed the trailing '/' in the links to the MCR about pages. This makes this repo consistent with dotnet-docker. This was a result of porting the URL formatting template from dotnet-docker

[MichaelSimons]

Merging ahead of CI as remaining legs are not affected by documentation changes.