UI/managed namespace changes

[chelshaw]

These changes include:

• un-editable namespace prefix on auth route, if managed
• redirect to base namespace (for logged in user) or managed namespace root if no namespace param is present

• Tests

When a root namespace is retrieved from endpoint and no namespace param is present, redirect:

[Monkeychip]

nice work so far!

[Monkeychip]

With octane you should be able to start writing these as Native classes (however, ignore me if we have to backport to prior to 1.7).
ex:

import Service from '@ember/service';

export default class ShoppingCartService extends Service {
}

[chelshaw]

Great catch, however we do indeed have to backport this to prior to 1.7 😭

[Monkeychip]

Nice work!