chore(components): update <post-menu> and <post-popovecontainer> to enforce separation of concerns

[myrta2302]

📄 Description

This PR updates the <post-popovercontainer> component by adding the following events:

• @event() postBeforeShow: EventEmitter<{ first?: boolean }>
• @event() postShow: EventEmitter<{ first?: boolean }>
• @event() postHide: EventEmitter
• @event() postBeforeToggle: EventEmitter<{ willOpen: boolean; }>
• @event() postToggle: EventEmitter<{ isOpen: boolean; }>

making use of the new animation implementation, based on the Web Animations API.

Additionally, the <post-menu> component has been updated to:

• Remove the use of requestAnimationFrame
• Reduce event listeners
• Directly consume events emitted by within the renderer (e.g. postToggle)

🚀Preview Link

https://preview-6357--swisspost-design-system-next.netlify.app/?path=/docs/8ca2bd70-56e6-4da9-b1fd-4e55388dca88--docs

📝 Checklist

• ✅ My code follows the style guidelines of this project
• 🛠️ I have performed a self-review of my own code
• 📄 I have made corresponding changes to the documentation
• ⚠️ My changes generate no new warnings or errors
• 🧪 I have added tests that prove my fix is effective or that my feature works
• ✔️ New and existing unit tests pass locally with my changes

[alizedebray]

I remove myself from the reviewer until both dependencies are merged (#6042 & #5586).

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud