Move ParseInfo to separate files

This is to make future addition to Attribution-Reporting-Info header
easier.

Change-Id: Ib0b6de08b4ca6b1f0f1b36321e8698a05da1b6b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5335624


Reviewed-by: Andrew Paseltiner <apaseltiner@chromium.org>
Reviewed-by: Nate Chapin <japhet@chromium.org>
Commit-Queue: Nan Lin <linnan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1267175}