Epic: Create diagnostics page

[jandubois]

Stories, ordered so we have a working PoC as soon as possible:

• Define the diagnostics object and create a couple sample checks (without fix actions for now) #2655
• Hook up diagnostics backend to UI - remove hard-wired sample diagnostics #2783
• Hook up diagnostics generation to app startup, preferences changes etc #2805
• Create initial UI to display the diagnostics #2656
• Add "fix action" callback to sample checks
• Update UI to support fix actions that may update the diagnostics object
• Create more comprehensive body of checks
• Diagnostics: Update UI in response to feedback #2913

There are several checks we could do automatically to verify that the local system is configured properly:

• Are the bundled utilities accessible from a user's shell?
• Are the files under ~/.docker/cli-plugins symlinks to ~/.rd/bin?
• Has the docker context been set to rancher-desktop (or not present, if the symlink in /var/run/docker.sock is in place)?
• Is the current kubectl context set to rancher-desktop?
• Is the API endpoint responding properly (docker socket on the host, containerd socket inside the VM, k3s socket on the host)
• (macOS) Is the external cluster IP on the bridged network?
• Does the host have an active internet connection (to pull k3s versions, and container images)?
• Is the docker-credential-* helper configured and working? Make sure it is not set to none.
• Are the log files growing beyond a reasonable size?
• Are we almost out of space inside the data volume?

This is just an initial brain-dump; there are probably more.

Any problems found should also display instructions how to debug this further and/or how to fix this.

See also brew doctor for other software providing a similar tool (but from the CLI).

[rak-phillip]

This might be related to #1217

[gaktive]

The "Run Diagnostics" command would be data driven so this could also be logged somewhere for a feature like a support bundle whereby people can easily spot errors.

[jandubois]

Moving this Epic to the following milestone.

Normally I would close it, and create a new one for the next release cycle, but this one has open issues referencing it, and I want to retain this information (for now).

[jandubois]

Ideas for additional checks have been moved to discussion in #3157.

We'll create a new epic for adding "fix actions" and other diagnostic improvements in the future.