Add support for creation of registry secret using RKE auth config type

[nwmac]

Summary

Fixes #13116

Technical notes summary

This PR adds support for creation of the rke.cattle.io/auth-config (RKE Auth Config) when setting a secret for the registry configuration on cluster creation.

Note we already showed RKE Auth config secrets in the drop-down, but we did not offer the user the ability to create them from the cluster creation screen - this has now been addded.

The changes are all in the SelectOrCreateAuthSecret component. The remaining code is to add a new E2E test for these changes.

Note the relevant e2e tests are also updated to delete the secrets and clusters that they create.

I also create the grammar on the create labels - I believe it should be 'an' and not 'a' for the options we have.

Areas or cases that should be tested

Cluster creation with registry configuration and RKE auth config secret auth.

Screenshot/Video

New option is added to the drop-down - see below:

Checklist

• [x ] The PR is linked to an issue and the linked issue has a Milestone, or no issue is needed
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[eva-vashkevich]

lgtm