Display error from shell command in popup box same as success

[Lyndon-Mackay]

Overview

The changes below are to make a popup box appear when the shell has an error in the same manner as a successful run.
Talked about in #7509
The status bar appears to have been improved since the issue was raised I have not seen "async job failed"

Testing

My test example was just typing from normal mode

• ":sh ls" for the normal case
• ":sh ls -garbage" for the error case.

Changes

I add a new callback type that returns an anyhow result
Changed the shell callback inner function to use the new callback type when shell output fails.

Alternative approach

My preferred approach is to modify EditorCompositorCallback to return a anyhow result with the rest of the code just returning the ok result.
That approach requires more work so I want to get feedback before I commit to it

Challenges

When callback defined in run_shell_command function returns an error result, it matches the error branch on add which doesn't have access to the editor or Compositor.