Add UI for admin creating organization/configuring messengers

[mattwr18]

Even before moving on to exposing UI for clients to have a scoped view of their organization and its records, we can expose the UI to create new organizations, including adding all encrypted messenger attrs. We can also expose UI for registering Signal and its associated setup.

Should be worked on after https://github.com/tactilenews/100eyes/issues/1947 to avoid unnecessary work.

[soey]

We could do this first, but I think having additional organizations beyond a singleton being set up does not bring any value if we have not scoped the UI

[mattwr18]

The value I was trying to put on it was that our team can have a walk through/organize how we will go from a dev-heavy approach to one less by someone else.