feat EPINIO-726: optional PVC deletion checkbox on app delete

[psanghvi17]

Summary

Fixes #EPINIO-726

Add an optional “Also delete PersistentVolumeClaims” checkbox (default unchecked) on application delete / bulk delete, and send deletePVC to the API.

Depends on API PR: epinio/epinio#3103

Occurred changes and/or fixed issues

• Single-app delete modal (AppDeleteModal) and prompt-remove flow gain a PVC deletion checkbox, default off.
• Bulk delete modal supports showDeletePVCOption and wires _deletePVC onto selected apps.
• Applications index enables the bulk PVC option.
• EpinioApplicationModel.remove and namespaced bulkRemove include deletePVC: true in the delete body when opted in.
• i18n keys added for PVC delete label/description; AppDeleteModal growl keys aligned to epinio.growl.application.delete.*.

Technical notes summary

• Mirrors the existing “Also delete image from registry” pattern (_deleteImage / deleteImage).
• Checkbox state resets when the modal opens/closes.
• Omitting the checkbox leaves API default (deletePVC false / unset).

Areas or cases that should be tested

Browser used locally: Chromium/Chrome (reviewer please use Firefox or Edge).

1. Delete one app with PVC checkbox unchecked → app deleted; PVCs remain (with API PR).
2. Delete one app with PVC checkbox checked → staging/app-data PVCs removed.
3. Bulk delete multiple apps with PVC option off/on → flags applied per selection; default off each open.
4. Combine image + PVC checkboxes (both off, one on, both on).
5. Prompt-remove path (if used in the shell) shows the new checkbox and passes the flag.
6. Non-application bulk delete modals do not show the PVC option unless enabled.
7. Success/error growls still display correctly after the i18n key rename.

Areas which could experience regressions

• Application delete / bulk delete request payloads (deleteImage / unbind / deletePVC).
• Bulk delete modal prop defaults for other resource types.
• Growl messaging after AppDeleteModal i18n key updates.
• Any custom delete flows that call remove/bulkRemove without expecting the new body field.