feat: use makeEnvironmentProviders for type-safe provideAuth0

[yogeshchoudhary147]

Description

This PR refactors the provideAuth0 function to return EnvironmentProviders instead of Provider[], enforcing type safety at compile-time and preventing incorrect usage in component providers.

Fixes #664

Changes

• Updated provideAuth0() to use makeEnvironmentProviders() and return EnvironmentProviders
• Updated return type from Provider[] to EnvironmentProviders
• Enhanced JSDoc documentation to explain the type safety benefit
• Updated EXAMPLES.md to reflect that this restriction is now enforced at compile-time

Motivation

Previously, developers could mistakenly add provideAuth0() to a component's providers array, which could lead to unexpected behavior and runtime issues. While the documentation warned against this, there was no compile-time
enforcement.

By using makeEnvironmentProviders, TypeScript now prevents this misuse:

Before (incorrect usage would compile):

@Component({                                                                                                                                                                                                                          
  providers: [provideAuth0()] // ⚠️ Compiles but incorrect                                                                                                                                                                            
})                                                                                                                                                                                                                                    
export class MyComponent {}                                                                                                                                                                                                           

After (incorrect usage produces a type error):

@Component({                                                                                                                                                                                                                          
 providers: [provideAuth0()] // ❌ Type error: EnvironmentProviders not assignable to Provider                                                                                                                                       
})                                                                                                                                                                                                                                    
export class MyComponent {}                                                                                                                                                                                                           

Benefits

• ✅ Type Safety: Compile-time prevention of incorrect usage
• ✅ Better DX: Developers get immediate TypeScript feedback
• ✅ Follows Angular Best Practices: Uses makeEnvironmentProviders as intended
• ✅ No Breaking Changes: Existing correct usage continues to work without modification

Testing

• ✅ All existing unit tests pass (7 suites, 122 tests)
• ✅ Build succeeds without errors
• ✅ No changes to public API surface beyond return type

Related

• Implements the solution proposed in Refactor the provideAuth0 function to return an EnvironmentProviders instead of Provider[] #664 by @LcsGa