Refactor unnecessary nested app folders

[rijkvanzanten]

When the app was first created, the decision was made to put every util/composable/component into a folder, with an index.ts file that would reexport the component:

import Example from './example.vue';

export { Example };
export default Example;

The idea behind this was that it would make the usage of these parts nicer, by allowing any:

import Example from '@/components/example';
import { Example } from '@/components/example';
import Example from '@/components/example/';
import { Example } from '@/components/example/';

However, in practice this is rather pointless. Dev tooling nowadays will autocomplete and resolve imports on your behalf, and this mixed usage turned into a bit of a messy import system, where different components would use different strategies. It also means that you can't properly rely on global searching, as the generic import means that components can import them under a different name. It also complicates testing coverage a bit, as there's a lot of needless imports/exports that need to be re-tested. This PR cleans that up to prepare for easier integration with testing suites coming soon.

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Also removing the outdated readme.md files that were scattered around the nested folders in favor of moving that into the docs