MegaMenu doesn't use SSR for dropdown content

[jancbeck]

• I have searched the Issues to see if this bug has already been reported
• I have tested the latest version

Steps to reproduce

1. Copy Mega Menu Default Example (server.tsx) to into Next.js Server Component (v14.2.2)
2. "View source" in browser

Current behavior

The content of the dropdown is only rendered when interacting with the dropdown trigger.

Expected behavior

The content of the dropdown should be pre-rendered on the server and hidden on page load.

Context

Hiding substantial parts of a site's main navigation can have terrible effects to search engine's indexability.

[SutuSebastian]

CC @tulup-conner