fix(xo-web/home/vm): show error toaster when deleting VMs failed

[pdonias]

Screenshots

• Deleting 1 VM with protection enabled from the home page:
  
• Deleting multiple VMs from the home page and some of them have the protection enabled:
  

Check list

Check if done, if not relevant leave unchecked.

• PR reference the relevant issue (e.g. Fixes #007 or See xoa-support#42)
• if UI changes, a screenshot has been added to the PR
• documentation updated
• CHANGELOG.unreleased.md:
  • enhancement/bug fix entry added
  • list of packages to release updated (${name} v${new version})
• I have tested added/updated features (and impacted code)
  • unit tests (e.g. cron/parse.spec.js)
  • if xo-server API changes, the corresponding test has been added to/updated on xo-server-test
  • at least manual testing

Process

1. create a PR as soon as possible
2. mark it as WiP: (Work in Progress) if not ready to be merged
3. when you want a review, add a reviewer (and only one)
4. if necessary, update your PR, and re- add a reviewer

From the Four Agreements:

1. Be impeccable with your word.
2. Don't take anything personally.
3. Don't make assumptions.
4. Always do your best.

[MathieuRA]

Why did you add screenshot of the blocked operation modal ?

[pdonias]

@MathieuRA When you only select one VM, deleteVms falls back to the deleteVm method that shows a modal when the operation is blocked and allows you to force it. I edited the PR description to clarify that.