Make the adminMeta object keys explicit

[timleslie]

This also removes the otherwise obsolete AdminUIApp.getAdminMeta() method (which technically makes this a breaking change).

[changeset-bot]

🦋 Changeset is good to go

Latest commit: 173cd5a

We got this.

This PR includes changesets to release 15 packages

Name	Type
@keystonejs/app-admin-ui	Major
@keystonejs/fields	Patch
@keystonejs/demo-project-blog	Patch
@keystonejs/demo-custom-fields	Patch
@keystonejs/demo-project-meetup	Patch
@keystonejs/demo-project-todo	Patch
@keystonejs/cypress-project-access-control	Patch
@keystonejs/cypress-project-basic	Patch
@keystonejs/cypress-project-client-validation	Patch
@keystonejs/cypress-project-login	Patch
@keystonejs/cypress-project-social-login	Patch
@keystonejs/example-projects-blank	Patch
@keystonejs/example-projects-nuxt	Patch
@keystonejs/example-projects-starter	Patch
@keystonejs/example-projects-todo	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR