feat: globalMiddleware option

[felix-dolderer]

🔗 Linked issue

Closes #114

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Adds a configuration option that adds a global middleware. This option requires being logged in for all pages (unless otherwise specified on the individual page)

Exposes and auto-imports the middleware functions (hankoLoggedIn, hankoLoggedOut) so they can be imported in a simple and typesafe way.

ℹ️ Help / Review wanted

1. I'm not sure if auto-importing the existing middleware functions (hankoLoggedIn, hankoLoggedOut) is necessary or the best way to make them accessible for building custom middleware on top of them.
2. How can I write tests for the logged-in behaviour? I logged in with my demo Hanko-API, took my current cookie and used that to make sure my tests were passing. This approach is obviously hard to replicate for other people who want to run the tests. (Addition: And it breaks automated testing.)