[xref-helper] Improve finite search

Expose the ability to add an API call to:

- https://learn.microsoft.com/_api/familyTrees/byPlatform/dotnet
- https://learn.microsoft.com/_api/familyTrees/byPlatform/java
- https://learn.microsoft.com/_api/familyTrees/byPlatform/javascript
- https://learn.microsoft.com/_api/familyTrees/byPlatform/python
- https://learn.microsoft.com/_api/familyTrees/byPlatform/powershell

These results dynamically return the filters used to scope searches more intelligently with this type of query string syntax:

https://learn.microsoft.com/api/apibrowser/dotnet/search?api-version=0.2&search=WithCommand&locale=en-us&$filter=monikers/any(t:%20t%20eq%20%27dotnet-aspire-9.1%27)

Where the query string section for the filtering is decoded as:

$filter=monikers/any(t: t eq 'dotnet-aspire-9.1')