Rationale:

### Clear peer dependencies

react, react-dom: These are needed for any React web app, and having a
single React version across your app is highly recommended.

### Possible peer dependencies

@elastic/eui, @emotion/react: If you are adding custom tabs, it makes
sense to use the same component library and CSS-in-JS solution as Feast UI,
and preferably the same versions and/or single instances (though I don't
know how important that is). Though using only @elastic/eui of these may
well be enough.

And you don't need these if you only want a custom projectListPromise. So
I'd mark these as optional peer dependencies.

### Not peer dependencies

@elastic/datemath, d3, inter-ui, moment, prop-types, query-string,
react-query, react-router-dom, react-scripts, use-query-params, zod: These
packages are for more specific purposes, and many of them you wouldn't
necessarily need in your app with the current customization possibilities,
and you could use different versions or even other alternatives.

Signed-off-by: Harri Lehtola <peruukki@hotmail.com>