fix: Exclude non-accessible types

[Dreamescaper]

Fixes #37 .

[Copilot]

Pull Request Overview

This PR fixes issue #37 by excluding non-accessible types from service registration generation. The change ensures that only types accessible from the calling context are included when the source generator scans for services to register.

Key changes:

• Added accessibility checks using SemanticModel.IsAccessible() to filter out non-accessible types
• Refactored GenerateAttributeSource to GenerateAttributeInfo with constants for better maintainability
• Added test cases to verify that internal and private classes are properly excluded

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
GenerateAttributeInfo.cs	Renamed class and converted properties to constants for metadata name and source
DependencyInjectionGenerator.cs	Updated references to use new class name and constants
DependencyInjectionGenerator.FilterTypes.cs	Added accessibility check using semantic model to exclude non-accessible types
TestServices.cs	Added internal test class to verify exclusion behavior
AddServicesTests.cs	Added private nested class test case with explanatory comment