Change help structure in dotnet test

[mariam-abdulla]

This pull request includes several updates to the dotnet-test command's help system to improve the organization and presentation of help options. The changes focus on refactoring methods for better clarity and functionality.

Refactoring and improvements to help system:

• src/Cli/dotnet/commands/dotnet-test/Terminal/TerminalTestReporter.cs: Added WriteOtherOptionsSection method to display additional help options in a structured format.
• src/Cli/dotnet/commands/dotnet-test/TestingPlatformCommand.Help.cs: Replaced WriteCustomHelp with WritePlatformAndExtensionOptions to separate platform and extension options more clearly. [1] [2]
• src/Cli/dotnet/commands/dotnet-test/TestingPlatformCommand.Help.cs: Added WriteHelpOptions method to streamline the help layout and improve readability.

These changes enhance the user experience by providing a more organized and comprehensive help output.

Relates to #45927

PR Overview

This PR refactors the help structure in the dotnet test command by splitting the help output into platform and extension options and updating the related reporting in the terminal.

• Split the original custom help into two methods: one for the overall help options and one dedicated to platform and extension options.
• Removed the old WriteCustomHelp method and its related helpers, integrating similar functionality into the new structure.
• Updated the TerminalTestReporter to use a new WriteOtherOptionsSection method that aligns with the new help layout.

Reviewed Changes

File	Description
src/Cli/dotnet/commands/dotnet-test/TestingPlatformCommand.Help.cs	Refactored help commands to separate built-in (platform) and extension options, integrating missing options display.
src/Cli/dotnet/commands/dotnet-test/Terminal/TerminalTestReporter.cs	Updated header and added a new WriteOtherOptionsSection method for displaying options help in the terminal.

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (2)

src/Cli/dotnet/commands/dotnet-test/TestingPlatformCommand.Help.cs:97

• The call to builtInOptions.Any() assumes builtInOptions is not null. Consider adding a null-check or defaulting to an empty list to avoid potential NullReferenceExceptions.

if (builtInOptions.Any())

src/Cli/dotnet/commands/dotnet-test/TestingPlatformCommand.Help.cs:103

• The call to nonBuiltInOptions.Any() assumes nonBuiltInOptions is not null. Ensure a null-check or use a default empty list to prevent possible runtime errors.

if (nonBuiltInOptions.Any())