Fix Unable to add extension tab to Edit Storage Class page

[aalves08]

Summary

Fixes #11122

Occurred changes and/or fixed issues

• Improve extension point for tabs to allow more use cases (also implement a "default" for locationConfig IF there's no mode specified)

Technical notes summary

Areas or cases that should be tested

• Add the following code to https://github.com/rancher/dashboard/blob/master/pkg/harvester-manager/index.ts:

plugin.addTab(
    TabLocation.RESOURCE_DETAIL,
    { resource: ['persistentvolumeclaim', 'storage.k8s.io.storageclass', 'configmap'] },
    {
      name:       'some-name',
      labelKey:   'generic.comingSoon',
      label:      'some-label',
      weight:     -5,
      showHeader: true,
      tooltip:    'this is a tooltip message',
      component:  () => import('./../../shell/components/BackLink.vue')
    }
  );

• Check that tabs are added ONLY in detail view mode and that it cover the scenario specified on the issue
• Check other general uses of the TAB extension point and make sure it works

Areas which could experience regressions

Screenshot/Video

Checklist

• The PR is linked to an issue and the linked issue has a Milestone, or no issue is needed
• The PR has a Milestone
• The PR template has been filled out
• The PR has been self reviewed
• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
• The PR has reviewed with UX and tested in light and dark mode, or there are no UX changes