Review Mozilla 1732388: support a proxy bypass flag for http requests

• Literally a proxy bypass >:[
• Related:
  • https://bugzilla.mozilla.org/show_bug.cgi?id=1732793
  • https://bugzilla.mozilla.org/show_bug.cgi?id=1733994
  • https://bugzilla.mozilla.org/show_bug.cgi?id=1732792
  • https://bugzilla.mozilla.org/show_bug.cgi?id=1733481

either revert or shim this flag to always be false looks like several other mozilla tickets depend on this one though so that's fun

We need to review these patches, and potentially gate any proxy bypasses behind MOZ_PROXY_BYPASS_PROTECTION and uplift any patch we write.