test: migrate l to vitest assertions api

[spliffone]

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Documentation.
Examples.
Dashboards Demo.
Playwright report.

Coverage Reports:

• charts-ng
• dashboards-ng
• element-ng
• element-translate-ng
• maps-ng
• native-charts-ng

[gemini-code-assist]

Code Review

This pull request refactors several Angular component test files to adopt the new signal-based input/output binding APIs and improve test assertions. The changes include migrating from ComponentRef.setInput() to inputBinding() and outputBinding() with signals, replacing vi.spyOn(component.instance.event, 'emit') with direct vi.fn() for outputs, and updating DOM assertions to use more semantic matchers like toHaveTextContent(), toHaveClass(), toBeDisabled(), and not.toBeInTheDocument(). A test case for handling an undefined link input in si-link.directive.spec.ts was removed during the refactoring and should be re-added to maintain test coverage.

[spike-rabbit]

Suggested change

	const heading = signal<TranslatableString>('Test heading');
	const heading: WritableSignal<string>;

and assignement in before each