[FEAT] Add onboarding modals for restaking & bridge pages

[yurixander]

Write up onboarding items for the restaking & bridge pages to help first time users quickly understand what the purpose and usage of the page is. It should be succinct but useful.

• [x] Implement onboarding modal logic and the ability to remember when it was previously seen
• [x] Add a help (?) button on the top right to allow users to re-open the onboarding modal in case they forget how to use the page.
• [x] Help button is hidden on pages that don't have onboarding defined
• [x] Add onboarding items for the nomination page
• [ ] Add onboarding items for the bridge page
• [x] Add onboarding items for the liquid staking page (added on #2570)
• [x] Add onboarding items for the restaking page

[AtelyPham]

We should add a checkbox for "not showing this modal in the future" and save this preference in local storage to enhance the user experience, as it can be frustrating for users if the modal reappears every time the page is refreshed.