Added LabeledSelectWithCreate and NamespaceSelect components

[eva-vashkevich]

Summary

Fixes #18510

Needed for rancher/virtual-clusters-ui#76

Occurred changes and/or fixed issues

Added new LabeledSelectWithCreate and NamespaceSelect components to standardize a namespace control that creates a new namespace in addition to allowing selecting existing ones.

Technical notes summary

There are more components that are doing similar logic (SelectOrCreateAuthSecret, persistentVolumeClaim/index.vue, credentials.vue) but they are different enough to not migrate at this time.
The point of this PR is to isolate this logic instead of re-inventing the wheel every time we need it, as we often run into the need to create namespaces while offering user to select one.

Areas or cases that should be tested

Mostly regression testing is required. There shouldn't be any noticeable change in behavior for the users when selecting existing or creating a new namespace.

Areas which could experience regressions

Any pages that use nameNsDescription component could be affected, but we don't need to test all of them.
make sure that the behavior is the same for core pages, like workload creation, chart installation, etc

Screenshot/Video

Checklist

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