Get structured data for GC Forms accounts onboarding / requesting to publish

## User story

As a **GC Forms client**,
I want to onboard efficiently, and minimize the amount of data I need to provide,
So that I can achieve my goal of trying GC Forms, publishing a form, or doing my work.

As a **GC Forms/Platform team**,
We want to support Platform efforts to align data standards with efficient, predictable and structured ways to select departments
So that data collection, management, analysis, and reporting needs and processes can be more aligned,
And help us get a better picture of our clients, their programs, and associated usage.

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## Context

We collect clients' organizations as unstructured data. This means there's manual transformation steps to make sure our data is aligned and clean.

We also make assumptions about departments and agencies based on email domains. What inferences can we make / mapping can we do to match domains to names/acronyms and organization numbers in the backend?

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## Description

- Collect more structured client data re: their department in a dropdown/searchable list
- Ensure only organizations that CDS/Platform can serve show up as options.
- Ensure legitimate user with domain we can serve, not shared email
- Consider prefilling/suggesting based on recognized domain
- Align with Notify / SSO
- Allow Platform to manage relationships in one system

> Only certain organizations are federal departments or agencies that Platform products can serve (only certain classes of GC organizations under the Financial Administration Act)

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## Acceptance criteria

- [ ] Bilingual names and acronyms
- [ ] Accessible with screenreader and keyboard
- [ ] Only includes organizations that CDS / Platform can serve (see FAA)
- [ ] Matches reference standard structure / naming
- [ ] Includes regional development agencies

Start by locating the GC Forms client onboarding and request-to-publish flows in this NextJS application, then review how organization data is currently collected. Compare the existing flow with the acceptance criteria for bilingual names, accessibility, serviceable organizations, reference-standard naming, and regional development agencies; done means the proposed structured selection supports those requirements.

Written by the indexing model from the issue text.