Add support for serving redirects for speculation rules prefetch.

This CL allows for prefetches with redirects to be served. After each
individual redirect is served, NavigationURLLoaderImpl interrupts the
current URL loader and allows all interceptors to try to intercept the
new navigation. Therefore, PrefetchStreamingURLLoader and
PrefetchURLLoaderInterceptor treat redirects and final response
differently.

Design Doc: https://docs.google.com/document/d/1VDo5GyoSrpntDKPLbqrTegpflsF5QDSGEkuY_IMMm6A/edit?usp=sharing

Bug: 1266876
Change-Id: I498b16758ff6f57cbe8262690474ebbf531a4004
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4346570
Commit-Queue: Max Curran <curranmax@chromium.org>
Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1120277}