feat(service-account): enable credentials to be saved as secret

[rkpattnaik780]

Enable kubernetes secret output for service-accounts.

Verification Steps

1. Create service-account with output-format

./rhoas service-account create --short-description k8s-secret --file-format secret

2. Reset credentials for a service-account

./rhoas service-account reset-credentials

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation change
• Other (please specify)

[wtrocki]

I totally missed that PR initially. Amazing work. Verified end to end.