Add Blazor analyzer to detect layout components that reference themselves

[Copilot]

Summary

Adds a new Blazor analyzer (LayoutCycleAnalyzer) to detect when layout components create infinite rendering loops by referencing themselves through the [Layout] attribute.

Problem

When a layout component references itself via the [Layout] attribute, it creates an infinite rendering loop at runtime. This commonly occurs when:

1. An _Imports.razor file contains @layout MyLayout
2. MyLayout.razor is defined in a subfolder and extends LayoutComponentBase

This results in generated code like:

[Layout(typeof(MyLayout))]
public class MyLayout : LayoutComponentBase
{
}

The LayoutView.Render() method follows the layout chain indefinitely, causing a stack overflow at runtime.

Solution

This PR introduces compile-time detection via a new analyzer:

• Diagnostic ID: BL0010 (Error severity)
• Detection: Identifies types extending LayoutComponentBase that have LayoutAttribute pointing to themselves
• Message: "Layout component '{0}' has a [Layout] attribute that references itself, which will cause an infinite rendering loop."

Example

Before (runtime failure):

[Layout(typeof(MyLayout))]
public class MyLayout : LayoutComponentBase
{
    // This compiles but crashes at runtime
}

After (compile-time error):

error BL0010: Layout component 'MyLayout' has a [Layout] attribute that references itself, which will cause an infinite rendering loop.

Changes

• Added LayoutCycleAnalyzer with comprehensive cycle detection logic
• Extended ComponentSymbols and ComponentsApi to support layout-related types
• Added BL0010 diagnostic descriptor with localized resources
• Added test coverage for all scenarios (self-reference, valid references, non-layout components)

Testing

All existing tests pass (64/64) with no regressions. Added 4 new tests covering:

• ✅ Self-referencing layout component (reports diagnostic)
• ✅ Layout component without attribute (no diagnostic)
• ✅ Layout component referencing different layout (no diagnostic)
• ✅ Non-layout component with layout attribute (no diagnostic)

Fixes the infinite rendering loop issue by moving detection from runtime to compile-time, providing early feedback to developers.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Blazor] Analyzer for detecting basic cycles in Layout components</issue_title>
<issue_description>If you put a @Layout MyLayout directive inside an _Imports.razor and MyLayout.razor is defined in a subfolder of that folder, you end up with something like this:

[Layout(MyLayout)]
public class MyLayout : LayoutBase
{
}

Creating an infinite rendering loop. We don't want to anything at runtime, but we can do something at compile time to detect this scenario.</issue_description>

<agent_instructions>The analyzer will simply check that no type extending LayoutBase has a Layout attribute applied that points to itself.</agent_instructions>

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

Fixes #63519

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