Add global rate limiting sample and much more

[64J0]

Description

[!WARNING] This is just experimental. To be honest I don't like this configuration that demands an empty list. I'll ask for more opinions before making this huge change to the Giraffe codebase.

With this PR, I'm:

• Adding a global rate limiting sample;
• Updating the code to work only with .NET 8 (due to the ASP.NET extensions);
• Adding the possibility to configure "ASP.NET extensions", which are middlewares like CacheOutput and RateLimiting, per route;
• Adding a new rate limiting sample that deals with this mechanism.

TODO:

• [ ] Filter repeated "ASP.NET extensions" to use the last value only;
• [ ] Update docs;
• [ ] Q: Is it possible to add OpenApi native configuration from ASP.NET?;
• [ ] Add automated tests.

How to test

Check the instructions at the sample's README.md.

Related issues

Related to https://github.com/giraffe-fsharp/Giraffe/issues/618.

[ebellani]

:+1:

[64J0]

I'm closing this PR in favor of more succinct ones, which I'll open later, tackling specific points of the ideas presented here.