Generate schema for custom configuration propertes to be respected by various IDEs for autocompletion.

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

This is basically the continuation of https://github.com/dotnet/aspnetcore/issues/2867.
The mentioned issue deals **only** with standard options supported by asp core. But what what about custom options?
As nuget package author I want my customers (developers) to enjoy the same intellisense experience as with standard options.

### Describe the solution you'd like

1. Provide class level attribute that during build time produces "schema instance" file of annotated class (custom Roslyn generator involved, introspects the annotated class and generates the file )
2. This schema instance file gets bundled automatically as nuget embedded resource.
3. Share the schema definition with IDE developers (VS, Rider, VS Code) and advise them to support autocompletion while editing app settings file by discovering the bundled schema resources files from all referenced nugets/projects , self included.

### Additional context

_No response_