Documentation and samples improvements to identity for .NET 8

A key deliverable to improve the experience of identity management in .NET is improved documentation. Our docs should provide a comprehensive guide that empowers developers to fully understand and utilize our identity management features. Deliverables will include samples for common scenarios that follow our recommended practices for enabling and integrating authentication and authorization in .NET. This issue will serve to track individual work items that roll up to this goal.

TODO (this list will grow as we iterate on the docs)

- [ ] Entry point (#29461) -flow to make it easier to find the right docs
- [x] Identity guidance (#29462) - new getting started experience
- [x] Identity solutions (#29453) - new index of known identity management products and services
- [ ] Identity endpoints
- [ ] ASP.NET Core identity overview - changes to better visualize and navigate
- [ ] Identity concepts - conceptual overview

Samples (TBD) - right now these are examples and not committed work.
- [ ] Angular with custom Angular UI for identity admin
- [ ] React with custom React UI for identity admin
- [ ] Mobile (.NET MAUI) access using tokens
- [x] Blazor WebAssembly Standalone - see [this PR](https://github.com/dotnet/blazor-samples/pull/110)
- [ ] Blazor Web App with External Login
- [ ] ASP.NET Core Web API
- [ ] Example that uses permissions/claims and not just "is authenticated"
- [ ] LDAP/Windows login

Stretch goals

- [ ] Backend for frontend pattern for identity in .NET
- [ ] Multi-tenancy with identity in .NET