Addressing feedback from extension author demonstration about a noticable pause waiting for extension execution to complete due to amount of time waiting on channel.
This commit expands upon the previous work by creating tests around extension command execution and how various extension update scenarios are handled.
Along the way, the logic handling formatting update messaging has been switched to use `ColorScheme` in order to honor color behavior flags.
Building on logic from the `gh ext list` for retrieving and assessing extension release information, this commit enhances the logic around invoking extensions to check for new releases.
Using the same user experience from checking `gh` version, this should only output information when the extension is used and gives the user information on how to upgrade depending on the type of extension and whether it is pinned or not.
```shell
andrewfeller@Andrews-MacBook-Pro cli % gh ext install dlvhdr/gh-dash --pin v4.6.0
✓ Installed extension dlvhdr/gh-dash
✓ Pinned extension at v4.6.0
andrewfeller@Andrews-MacBook-Pro cli % ./bin/gh dash
A new release of dash is available: 4.6.0 → 4.7.0
To upgrade, run: gh extension upgrade dash --force
https://github.com/dlvhdr/gh-dash
```
