"Has a provisioner set" validation check should look for executable-level provisioners in the absence of a DefaultProvisioner

[arunsathiya]

op CLI version

2.19.0-beta.01

Goal or desired behavior

When a Shell Plugin's DefaultProvisioner is set to nil, the "Has a provisioner set" validation check fails. We should update that check to look for an executable-level provisioner in the absence of a default one.

Two examples of Shell Plugins that'll benefit from this improvement are MySQL and Akamai:

• update(mysql): Move provisioner to the executable-level CredentialUsage configuration #293
• update(akamai): Move provisioner to the executable-level CredentialUsage configuration #294

Current behavior

"Has a provisioner set" validation checks fails.

Relevant log output

No response