docs(angular): config provider usage and content updates

[sean-perkins]

Revamps the documentation surrounding the Config provider and usage in Angular. If we agree with the general layout and content adjustments, I can make similar changes to React and Vue.

Related issues: #2580

Quick preview: https://ionic-docs-git-docs-angular-config-ionic1.vercel.app/docs/angular/config

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Name	Status	Preview	Updated
ionic-docs	✅ Ready (Inspect)	Visit Preview	Oct 19, 2022 at 5:02PM (UTC)

[brandyscarney]

I'm not crazy about the formatting for the API reference & Interface, but the content additions look good to me.

[sean-perkins]

Do we have an example of someone who does "API Reference" and type documentation really well that perhaps we could get inspiration from?

The formatting for the API reference is from Vue's router docs: https://router.vuejs.org/api/index.html#uselink.

I'm open to thoughts here on how to make this easier to reason about. The goal is to inform developers about the available Config provider and the public methods on it.

Documenting the config interface types is both for knowing which keys are available and what they do. The downside to the table mark-up, is we cannot just copy/paste our interface when we make changes. We need to vet the table and identify missing/outdated config keys and/or documentation comments.

[brandyscarney]

Dropping a link to an API reference Ben sent in Slack for future reference: https://mui.com/material-ui/customization/theming/#api