bootstrap: Fix error msg when the Git token doesn't match the repo owner

[somtochiama]

When running flux bootstrap with the wrong user (and the repository already exists) returns this confusing error because
ggp tries to create the repository under the authenticated user.

flux bootstrap github --owner=soule --token-auth --repository=fleet-infra --personal
► connecting to github.com
✗ failed to create new Git repository "https://github.com/soule/fleet-infra": multiple errors occurred:
- POST https://api.github.com/user/repos: 422 Repository creation failed. [{Resource:Repository Field:name Code:custom Message:name already exists on this account}]
- resource already exists, cannot create object. Use Reconcile() to create it idempotently

With these changes, we give a better error

./bin/flux bootstrap github --owner=soule --token-auth --repository=fleet-infraxx --personal
► connecting to github.com
✗ failed to create new Git repository "https://github.com/soule/fleet-infraxx": the specified owner 'soule' doesn't match the identity associated with the given token

Closes: #3867

[makkes]

This is much better than before. One thing we could still improve on would be that the message ✗ failed to create new Git repository "https://github.com/soule/fleet-infraxx": incorrect owner 'soule' passed in isn't very actionable because the user did want to create the repo under that user's account so strictly speaking it's not an "incorrect owner", is it?

[stefanprodan]

Please squash the two commits.

[somtochiama]

because the user did want to create the repo under that user's account so strictly speaking it's not an "incorrect owner", is it?

More like the wrong string is passed into the --owner flag. We can check for the error and return a better error msg.
@makkes Is something like please pass correct username when using --personal flag better?
and I have updated the description. This is the error that is returned: incorrect user 'soule' provided

[stefanprodan]

LGTM

Thanks @somtochiama 🏅

[stefanprodan]

Maybe the specified owner X doesn't match the identity associated with the given token is more accurate?

[stefanprodan]

@somtochiama please make the changes upstream, we'll do another patch release of ggp then you can update this PR.

needs changes upstream

[fluxcdbot]

Successfully created backport PR for release/v2.1.x:

• [release/v2.1.x] bootstrap: Fix error msg when the Git token doesn't match the repo owner #4325