Add blazor with web worker template

[ilonatommy]

Add WebWorker support to Blazor project templates

This PR adds a --webworker parameter to the Blazor project templates (blazor and blazorwasm), enabling developers to create Blazor applications with Web Worker support out of the box, to offload heavy tasks.

Description

New template parameter:

--webworker - Adds a WorkerClient project and sample ImageProcessor page demonstrating Web Worker capabilities

Usage:

# Create a Blazor Web App with WebWorker support
dotnet new blazor --webworker

# Create a Blazor WebAssembly standalone app with WebWorker support  
dotnet new blazorwasm --webworker

For basic scenarios, user does not need to edit the web worker library (BlazorWebCSharp.1.WorkerClient) contents, they only edit:

• The parameters passed to InvokeAsync method:

var processedPixels = await WorkerClient.InvokeAsync(
                "BlazorWebCSharp._1.Client.Worker.GrayscaleWorker.ApplyGrayscale",
                originalPixels,
                _intensity);`

• Create their own heavy-job c# code, similar to GrayscaleWorker.ApplyGrayscale that is passed to the WorkerClient invocation methods.

The basic scenario supports bytes[] return type.

Fixes dotnet/runtime#95452