Enhance glab with new workspace commands to output OAuth2.0 access token
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The `glab` CLI needs to be enhanced to support the following command
```sh
glab workspaces ssh show-credentials
```
This command would show the OAuth2.0 access token for the user. If the user has not logged into `glab` via OAuth2.0, it should then invoke the OAuth2.0 flow used by the command `glab auth login`
issue