✨ Placeholder pages - Githubissues

✨ Feature

Let's create all the placeholder pages along with any shared content.

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

[ ] Pages from "Basic details" to "Submit pitch" created
[ ] Hero, title, subtitle, breadcrumbs created for each.
[ ] Space for stepper added
[ ] "Save and exit" link added
[ ] Space for candidate count added
[ ] Shared layout? Shared components?
[ ] desire to make switching as fast and seamless as possible
- [ ] use react router portal?
- [ ] animate left-right?

Issues which must be completed before this one.

### Blocked By
- [ ] https://github.com/GCTC-NTGC/gc-digital-talent/issues/10749
- [ ] https://github.com/GCTC-NTGC/gc-digital-talent/issues/10742