fix(vmware-explorer): better handling of VM import without any storage

[fbeauchamp]

Description

from support 18963 , log :

esxi.listVms
{
  "host": "* obfuscated *",
  "user": "* obfuscated *",
  "password": "* obfuscated *",
  "sslVerify": false
}
{
  "message": "Cannot read properties of undefined (reading 'perDatastoreUsage')",
  "name": "TypeError",
  "stack": "TypeError: Cannot read properties of undefined (reading 'perDatastoreUsage')
    at file:///usr/local/lib/node_modules/xo-server/node_modules/@xen-orchestra/vmware-explorer/esxi.mjs:238:55
    at Array.map (<anonymous>)
    at Esxi.getAllVmMetadata (file:///usr/local/lib/node_modules/xo-server/node_modules/@xen-orchestra/vmware-explorer/esxi.mjs:236:31)
    at Api.#callApiMethod (file:///usr/local/lib/node_modules/xo-server/src/xo-mixins/api.mjs:445:20)"
}

Checklist

• Commit
  • Title follows commit conventions
  • Reference the relevant issue (Fixes #007, See xoa-support#42, See https://...)
  • If bug fix, add Introduced by
• Changelog
  • If visible by XOA users, add changelog entry
  • Update "Packages to release" in CHANGELOG.unreleased.md
• PR
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  • If not finished or not tested, open as Draft