Update documentation for RoslynDeployment startup project and fix outdated references

[Copilot]

Fixes #<issue_number>

Changes

This PR updates the "Building, Debugging and Testing on Windows" documentation to address outdated information and improve clarity around the RoslynDeployment project.

What was fixed:

1. Removed outdated project reference: The documentation mentioned Roslyn.VisualStudio.InteractiveComponents, which no longer exists in the codebase and has been removed.

2. Added explicit setup instructions: The docs now include clear instructions on how to set RoslynDeployment as the startup project: "right-click the RoslynDeployment project in Solution Explorer and select 'Set as Startup Project'".

3. Clarified what RoslynDeployment is: Added an explanation that RoslynDeployment is a container project located in src/Deployment that bundles and deploys all the main Roslyn extensions together, giving developers a complete debugging experience when pressing F5.

4. Fixed incorrect folder paths:

   • Compilers\Packages → Compilers\Extension
   • ExpressionEvaluator\Setup → ExpressionEvaluator\Package
   • VisualStudio → VisualStudio\Setup

5. Improved formatting: Used bold emphasis on RoslynDeployment for better visibility and restructured the text for better readability.

The documentation already mentioned RoslynDeployment as mentioned in PR #28016, but as noted by @jaredpar, it needed updating to reflect current project structure and provide clearer guidance for contributors.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Should documentation be updated with info about the RoslynDeployment project?</issue_title>
<issue_description>As far as I can tell from #28016, the RoslynDeployent project (originally called just "Roslyn") should be the default when running a custom build of Roslyn. But the article Building, Debugging and Testing on Windows does not mention the project at all. Should the article be updated?</issue_description>

<agent_instructions>Copilot, can you make this change, but only if needed. Effectively, a user will want this to be set as the 'startup' project in VS so that they can F5 and debug a live instance of visual studio with their changes.

If the docs already mention this, there's no need to do anything.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@jaredpar Yes that should be changed. It appears to be a bit out of date.

Fixes #30267

---

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.

[CyrusNajmabadi]

@dotnet/roslyn-ide ptal.