Redesign the general request form for tribes where users select an org name

[h-m-f-t]

Sub-issue description

In the general request form, tribes are asked to select their organization type (tribal), then asked to tell us their organization name. We know the names of all federally recognized tribes and have a healthy set of state-recognized tribe names.

Let's redesign what tribal requestors experience in the form to reflect a situation where we have them select their names upfront, only typing a name in if it isn't found in the list. We should also consider other impacts of these choices on other sections of the form (like "Organization" or "Senior official").

Acceptance criteria

• Review the "🕹️ Control through selection" section of the "Enterprise mode by default" paper (public, internal)
• Sketch/wireframe/mock-up an updated flow. Rough is ok!
• Get feedback from product, design, engineering (consider time in workshop), then iterate on feedback
• Make a follow-up sub-issue in Enterprise mode by default for a single org type: tribes #4755 to continue the work
  • This might be more design work or could be an implementation issue

Additional context

• The "🕹️ Control through selection" section of the "Enterprise mode by default" paper has a lengthy discussion of some of our desired outcomes.