Remove Blazor Hosted & WebAssembly apps, assets, and configs

This commit removes the Blazor Hosted Server and WebAssembly applications, along with their associated files, assets, and configurations:
- Deleted `BlazorBootstrap.Demo.Hosted.Server` and `BlazorBootstrap.Demo.Hosted.Client` projects.
- Removed routing logic, startup code, and launch settings.
- Deleted application settings (`appsettings.json`, `appsettings.Development.json`).
- Removed Razor pages (`_Host.cshtml`, `Error.cshtml`) and controllers.
- Deleted image assets (`placeholder.png`, multiple icons, and logos).
- Removed `sitemap.xml` and other project-specific files.
- Updated `blazorbootstrap.sln` to reflect project removals.

These changes indicate the decommissioning or migration of the Blazor Hosted and WebAssembly applications.

Author: gvreddy04