Exclude special-use domains from proxy

[cohesive-flight]

The extension currently proxies special-use domains, such as home.arpa, causing them to be inaccessible unless set to never be proxied. There's also the .internal TLD, which is reserved for private-use.

[ruihildt]

Can you check if this is still the case with the latest release?

[cohesive-flight]

It is still an issue with the latest release.

[ruihildt]

Sorry I didn't look more in depth first, it turns out the only domain I exclude manually is "localhost". The main logic of excluding local traffic is IP based.

Ideally I would prefer to use a third-party library, since this is definitely not my area of expertise, but in any case, I can hard-code the whole list as well.

Reference: https://www.rfc-editor.org/rfc/rfc6761.html