Upgrade to latest Azure Functions SDK

[shibayan]

This pull request includes several updates to the Azure Functions sample projects and the core libraries. The most important changes include updating package versions, refactoring code for improved readability, and modifying project configurations.

Package Updates:

• Updated Microsoft.NET.Sdk.Functions to version 4.6.0 in several sample projects (BasicSample.csproj, ProxySample.csproj, VirtualPathSample.csproj, WebsiteSample.csproj). [1] [2] [3] [4]
• Updated Microsoft.Azure.Functions.Worker and Microsoft.Azure.Functions.Worker.Sdk to version 2.0.0 in IsolatedSample.csproj.
• Updated Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore to version 2.0.0 in Functions.Worker.Extensions.HttpApi.csproj.

Code Refactoring:

• Simplified null-check in AddHttpApi method by using ArgumentNullException.ThrowIfNull in HttpApiBuilderExtensions.cs.
• Refactored HttpFunctionBase class declarations to use semicolon syntax in HttpFunctionBase.cs files. [1] [2]

Project Configuration:

• Modified Program.cs in IsolatedSample to use FunctionsApplication.CreateBuilder and added comments for enabling Application Insights.

Code Improvements:

• Removed unnecessary private logger field and directly used the parameter logger in Function1.cs.