feat: add support for Angular signal inputs and outputs

[PieterjanDeClippel]

Summary

This PR adds support for Angular 17.1+ signal-based inputs and outputs in mock components.

Files Created:

• libs/ng-mocks/src/lib/common/decorate.signal-inputs.ts - Handles decoration of signal inputs on mock components
• libs/ng-mocks/src/lib/common/decorate.signal-outputs.ts - Handles decoration of signal outputs on mock components
• tests/signal-inputs-outputs/test.spec.ts - Test file for signal inputs/outputs

Files Modified:

• libs/ng-mocks/src/lib/common/core.types.ts - Added SignalInputDef and SignalOutputDef types
• libs/ng-mocks/src/lib/resolve/collect-declarations.ts - Added parsing of signal inputs/outputs from Angular's internal ɵcmp/ɵdir metadata
• libs/ng-mocks/src/lib/mock/decorate-declaration.ts - Added calls to decorate signal inputs/outputs

How it works:

1. Detection: The code parses Angular's internal component/directive definitions (ɵcmp, ɵdir) to find signal inputs/outputs which have isSignal: true in their metadata
2. Signal Inputs: Creates writable signals on the mock prototype so tests can both read and write values
3. Signal Outputs: Creates mock OutputRef objects that support subscribe() and emit() methods for testing

Usage in tests:

// For signal inputs - the mock will have writable signals
const mockChild = ngMocks.findInstance(SignalChildComponent);
mockChild.signalInput.set('new value'); // Set signal input value

// For signal outputs - the mock has emit() method
mockChild.signalOutput.emit('test value'); // Emit from output

The implementation maintains backward compatibility - it only activates for components that use signal inputs/outputs (Angular 17.1+).

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Split from PR #12594 which combines both Angular 21 upgrade and signal support

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