Add account e2e tests

[JillRegan]

✨ Summary

• Adds E2E test TestAccItemResourceWithAccount which uses desktop auth to get items.
• This test can only be run locally and user needs to create a vault called Terraform Test Vault in order to run

🔗 Resolves:

• Creates test for desktop auth with SDK

✅ Checklist

• 🖊️ Commits are signed
• 🧪 Tests added/updated: (See the Testing Guide for when to use each type and how to run them)
  • 🔹 Unit /🔸 Integration
  • 🌐 E2E
• 📚 Docs updated (if behavior changed)

🕵️ Review Notes & ⚠️ Risks

• Can only be tested locally, is skipped in the pipeline

[volodymyrZotov]

This test can only be run locally and user needs to create a vault called Terraform Test Vault in order to run

Could you mention this in docs/testing/testing.md, please?

Can be done in a followup PR, as I we also need to update there instructions about setting Connect env vars.

[volodymyrZotov]

Let's add the same check for OP_TEST_VAULT_NAME env var, so it doesn't run tests if it's not set.