Port app-modal to harvester shell (backport #1163)

[mergify]

Summary

Rancher dashboard has already replace <modal> to <app-modal> in below two PRs

• Replace modal implementation in PromptModal.vue rancher/dashboard#10556
• Replace vue-js-modal with app-modal rancher/dashboard#10591

PR Checklist

• Is this a multi-tenancy feature/bug?
  • Yes, the relevant RBAC changes are at:
• Do we need to backport changes to the old Rancher UI, such as RKE1?
  • Yes, the relevant PR is at:
• Are backend engineers aware of UI changes?
  • Yes, the backend owner is:

Related Issue #
[BUG] Can't select the harvester version to upgrade in Rancher UI
[BUG] Rancher doesn't use dark mode in popup modals when in Harvester UI

Screenshot/Video

I've tested harvester

• upgrade modal ✅
• all modals in vm edit page ✅
• generate support bundle modal✅
• Novnc customKey modal✅

Test on embedded mode

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This is an automatic backport of pull request #1163 done by [Mergify](https://mergify.com).