Fix proxy redirection loop detection

[adomasven]

• When capturing requests via webRequest, we are missing any prefetched pages and are not properly redirecting, so we switch to webNavigation
• webNavigation doesn't have request headers, but we only use them for redirection loop detection and we have a better way to prevent that now anyway

Report https://forums.zotero.org/discussion/113353/proxy-redirection-gets-disabled-by-a-detected-redirect-loop-on-the-wikipedia-library

@AbeJellinek Would you test on-site to see if the redirect-loop rule is correctly triggered there?

[AbeJellinek]

:'(

Was this happening with any other proxies?