OSOE-1208: Use our own .NET SDKs

[sarahelsaig]

OSOE-1208

[github-actions]

This pull request appears to contain breaking changes.

• If you can do this without breaking changes, then please do that, it'd be better.
• If breaking changes are inevitable, then add an explanation of these and a migration guide for users to the description of the pull request (during the next release, these will be added to the release notes). A CompatibilitySuppressions.xml file was generated for each project with breaking changes that you can download from the artifacts and use to suppress further such warnings.
• If the changes are technically breaking but not something that would actually be breaking for consuming projects (like the signature of a constructor changing due to new injected dependencies) then also take the generated CompatibilitySuppressions.xml file and add the ignore-breaking-changes label too, the push another commit. Furthermore, consider how in the future this can be avoided: Can perhaps the class be made internal (what's usually better for implementations of interfaces for injected dependencies)?