Correctly configuring .NET SDK(s) in a Linux environment

We need to get clear instructions and some testing in place for correctly installing one or more .NET SDK versions on Linux, with a bias to Ubuntu. We had some [reports](https://github.com/dotnet/sdk/issues/44901) of this not going well. We're going to use this issue as the official tracking issue.

We need the following:

- Clear instructions, targeting a variety of distros/versions.
- Validate that various environments work correctly, such as: raw metal, GitHub runners, WSL, Docker, dev containers.
- Publish the final experience as a blog post

We had discussed this recently. The reports now provide "accelerated motivation".

Instructions (growing list over time):

- [Install .NET on Ubuntu 22.04](https://gist.github.com/richlander/3ee8669a47ebbcf8bccb877061a00913)
- [Install .NET on Ubuntu 24.04](https://gist.github.com/richlander/62f9d9261eb3709909fbc35c86cdaa6d)

Relevant announcements:

- https://github.com/dotnet/core/discussions/9556
- https://github.com/dotnet/core/discussions/9258