Enforce non-overlap between IGs and NegativeIGs in joinAdInterestGroup.

This change enforces the policy that interest groups must be distinct
from negative interest groups for efficiency of storage. This is
enforced during the call to joinAdInterestGroup and subsequent updates
by applying the restriction that an InterestGroup can provide a value
for additionalBidKey or ads, but not both.

Bug: 1464874
Change-Id: If8d191cc72776f543112c677c2aac8898186dda5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4843371
Reviewed-by: Maks Orlovich <morlovich@chromium.org>
Commit-Queue: Orr Bernstein <orrb@google.com>
Cr-Commit-Position: refs/heads/main@{#1193693}