che: GitHub authentication fails in VS Code if there is no PAT or if PAT has expired

@RomanNikitenko here is another video that I have just recorded on the dogfooding instance. Let me know what other information I can provide you to help you reproduce it:

https://user-images.githubusercontent.com/606959/229379176-4897cf6f-a06b-457c-9879-393b1bbf8387.mp4

We discussed briefly with @RomanNikitenko and we have decided to display an informative message to the user with the root cause of the problem and the instructions to fix it rather than implement the automatic update (that would probably require some work che-server side):

If the token has expired and is managed by Che

The GitHub token included in the workspace file '<token-path>' has expired. 
Restarting the workspace will automatically update the file with a new GitHub token.

If the token has expired but is NOT managed by Che

The GitHub token included in the workspace file '<token-path>' has expired. 
The expired token is stored in the secret <secret-name> and needs to be updated with a new one.

If the token is not present and the workspace is managed by Che

A valid GitHub token stored in file '<token-path>' is required for this feature to work.
Please reference to this [Eclipse Che documentation article](https://www.eclipse.org/che/docs/stable/end-user-guide/using-a-git-provider-access-token/) to learn how to automatically include one in your workspaces.

If the token is not present and the workspace is NOT managed by Che

A valid GitHub token stored in file '<token-path>' is required for this feature to work.
Please reference to this [DevWorkspace Operator documentation article](https://github.com/devfile/devworkspace-operator/blob/main/docs/additional-configuration.adoc#adding-git-credentials-to-a-workspace) to learn how to create a secret to automatically include one in your workspaces.