upcoming: [UIE-9597] - IAM Parent/Child: Align proxy logic with delegate users

[abailly-akamai]

Description 📝

In the new model, proxy users (user_type from the /profile response) become delegate users. When it comes to UI, it's pretty much a 1/1 relationship for Cloud Manager to provide the same experience.

This PR takes a progressive, which is matching the proxy logic to delegates users, without deprecating proxy users since we will still server them for some time. (the concept of proxy users will be fully deprecated in a subsequent PR, once that change is made in APIv4).

Changes 🔄

• Align proxy logic with delegate users ('user_type" = 'proxy' OR 'user_type" = 'delegate')
• Change naming conventions to reference userType rather than user or account in order to better align with APIv4 naming conventions and facilitate core reading logic comprehension

Scope 🚢

Upon production release, changes in this PR will be visible to:

• All customers
• [] Some customers (e.g. in Beta or Limited Availability)
• No customers / Not applicable

How to test 🧪

Prerequisites

• Have a legacy Parent/Child account
• Have an IAM Parent/Child account

Verification steps

Legacy Parent/Child account

• ✅ Confirm there is no regression in the experience as a parent or proxy user

IAM Parent/Child account

• ✅ Confirm being able to switch account (back and forth between Parent & Delegate)
• ✅ Confirm UI behaves properly as a delegate user

Author Checklists

As an Author, to speed up the review process, I considered 🤔

👀 Doing a self review
❔ Our contribution guidelines
🤏 Splitting feature into small PRs
➕ Adding a changeset
🧪 Providing/improving test coverage
🔐 Removing all sensitive information from the code and PR description
🚩 Using a feature flag to protect the release
👣 Providing comprehensive reproduction steps
📑 Providing or updating our documentation
🕛 Scheduling a pair reviewing session
📱 Providing mobile support
♿ Providing accessibility support

• I have read and considered all applicable items listed above.

As an Author, before moving this PR from Draft to Open, I confirmed ✅

• All tests and CI checks are passing
• TypeScript compilation succeeded without errors
• Code passes all linting rules

[linode-gh-bot]

Cloud Manager UI test results

🎉 865 passing tests on test run #7 ↗︎

❌ Failing	✅ Passing	↪️ Skipped	🕐 Duration
0 Failing	865 Passing	11 Skipped	39m 18s