✨ Add personality to context

          The code looks great! I like the use of `personality`. Feels like something we might want to expand on and put into a context.

Originally posted by @tristan-orourke in https://github.com/GCTC-NTGC/gc-digital-talent/pull/6999#pullrequestreview-1484484652

✨ Feature

PR #6999 added the idea of an app personality that changes the theme, copy, navbar, and home link. In that PR it was implemented by a simple URL query param that was checked for on a few pages. It would probably be better to add this to a context to make this easier and more consistent to expand as necessary.

If the personality is changed to IAP before navigation it could reduce the flicker of theme changes during navigation as well.

🕵️ Details

Add any additional details that could assist with the development of the new feature.

:question: Questions

Visiting the IAP home page switches the personality to IAP?
What causes the personality to switch back to default?
Other than the copy and theme on the login and register pages what else changes with the personality? The home link in the nav? The theme in the application process?

🎨 Design File

Include a link to the design file (if it exists).

📸 Screenshot

Add a screenshot of the new feature (if possible).

🙋‍♀️ Proposed Implementation

(optional) Do you have a proposed implementation?

🌎 Localization

(optional) Provide any new copy along with translations available.

✅ Acceptance Criteria

[ ] Personality is added to the context
[ ] Personality can be switched between "iap" and "default"
[ ] Login page can change theme, nav, and copy with IAP personality

GCTC-NTGC / gc-digital-talent