[MAUI Blazor] Decide whether to support host pages located outside the content directory root

[MackinnonBuck]

MAUI Blazor uses the location of the host page (usually index.html) to determine where the root of the content directory is: https://github.com/dotnet/maui/blob/5105c37657b6be602e76988631cc159687cf4be9/src/BlazorWebView/src/Maui/Windows/BlazorWebViewHandler.Windows.cs#L59-L62

Currently, using a host page located in an RCL or a subdirectory of wwwroot/ causes static content requests to 404. This can be partially worked around by changing URLs to be relative to the host page location, but this obviously only works for URLs that can be expressed as such.

We could either:

• Keep the existing behavior:
  1. Document that the host page should always be placed directly in wwwroot/
  2. Consider providing better errors/warnings when attempting to do otherwise
• Add new APIs to allow manually specifying the root of the content directory

Related: https://github.com/dotnet/maui/issues/8613

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[Eilon]

Some more notes in this doc issue: https://github.com/dotnet/AspNetCore.Docs/issues/27819#issuecomment-1335870663