[Blazor] Blazor single project experience follow ups

[javiercn]

We already checked-in initial support for the single project experience in the SDK. Based on exploratory testing with the template, we've discovered a set of issues we need to address to get into a functional template:

• Fix service worker being incorrectly included. [Blazor] Fix condition for including the service worker assets in the project #49076
• Set StaticWebAssetBasePath unconditionally to / in multi-targeting builds on the .NET 8.0 project. [Blazor] Fixes for the unified project experience within Blazor projects/apps sdk#33649
• Put the embedded configuration rule in the web SDK [Blazor] Fixes for the unified project experience within Blazor projects/apps sdk#33649

  <ItemGroup>
   <StaticWebAssetsEmbeddedConfiguration
     Include="$(TargetFramework)"
     Condition="'$([MSBuild]::GetTargetPlatformIdentifier($(TargetFramework)))' == '' And $([MSBuild]::VersionGreaterThanOrEquals(8.0, $([MSBuild]::GetTargetFrameworkVersion($(TargetFramework)))))">
     <Platform>browser</Platform>
   </StaticWebAssetsEmbeddedConfiguration>
  </ItemGroup>
  

• Adjust the conventions on the targets. Fix similar conventions for content [Blazor] Fixes for the unified project experience within Blazor projects/apps sdk#33649

  <ItemGroup Condition="'$([MSBuild]::GetTargetPlatformIdentifier($(TargetFramework)))' != 'browser'">
    <Compile Remove="**\**\*.Browser.cs" />
    <Compile Remove="**\Browser\**\*.cs" />
  </ItemGroup>
  
  <ItemGroup Condition="'$([MSBuild]::GetTargetPlatformIdentifier($(TargetFramework)))' != ''">
    <Compile Remove="**\**\*.Server.cs" />
    <Compile Remove="**\Server\**\*.cs" />
  </ItemGroup>
  

• Resolve conflicts on the template
  • App styles bundle. Covered as part of Static web assets SDK support for multi targeting conventions #47885
  • Configuration files. We need to update the Wasm SDK to provide a AssetMergeBehavior
• Get rid of the loading UI Default WebAssembly loading progress indicator doesn't apply in Blazor Web template #49056

[SteveSandersonMS]

Also: Razor tooling behaves unpredictably when multitargeting and misses completions