What kind of change does this PR introduce?

Feature (new extended template diagnostic)

What is the current behavior?

When a template reference variable (#name) has the same name as a component class property or method, there is no warning. This can lead to confusion, because inside the template the reference variable takes precedence over the class member.

For example:

@Component({
  template: '<div #name>{{ name }}</div>'
})
export class MyComponent {
  name = 'Angular';
}

Here {{ name }} resolves to the template reference (the <div> element), not the string 'Angular'.

Closes #45227

What is the new behavior?

A new extended template diagnostic (templateReferenceShadowsClassMember, NG8119) warns when a template reference variable shadows a component class member. The warning covers:

• Direct class properties and methods
• Inherited properties from base classes
• Private, protected, and public members

The diagnostic is emitted as a warning (not an error), consistent with other extended diagnostics.

Additional context

A previous PR (#48658) attempted this but was closed due to missing cases (inherited properties, template variable scoping). This implementation:

• Uses TypeChecker.getTypeAtLocation() + getProperty() which automatically resolves inherited members
• Reports on the keySpan of the reference for precise source mapping
• Includes comprehensive tests covering inheritance, access modifiers, methods, and negative cases