[WIP] Implement Zitadel IDP

[Foxtrek64]

Closes #350

This PR implements an Aspire integration to add support for the Zitadel IDP (https://zitadel.com).

PR Checklist

• Created a feature/dev branch in your fork (vs. submitting directly from a commit on main)
• Based off latest main branch of toolkit
• PR doesn't include merge commits (always rebase on top of our main, if needed)
• New integration
  • Docs are written
  • Added description of major feature to project description for NuGet package (4000 total character limit, so don't push entire description over that)
• Tests for the changes have been added (for bug fixes / features) (if applicable)
• Contains NO breaking changes
• Every new API (including internal ones) has full XML docs
• Code follows all style conventions

Other information

[Foxtrek64]

This PR contains a couple missing features currently:

• Docs have yet to be written
• Tests have yet to be written
• There is no integration with a CockroachDB or PostgreSQL database for Zitadel to store data.
• Health check has not yet been implemented.

I had these in my original code, but it seems to have been lost to time so I've needed to recreate it from scratch.

[davidfowl]

Take a look at how the other resources implement default passwords. None are hardcoded and we do random password generation. https://github.com/dotnet/aspire/blob/cf14299e30838ccfd369ee416c5d962409fd4e5a/src/Aspire.Hosting.MySql/MySqlBuilderExtensions.cs#L35

[Foxtrek64]

Saw that. Wasn't sure if I should use the documented default value or generate it. I'll switch to the generated password.