[unified-consent] Disable Unified Consent if kSyncUserConsentSeparateType is disabled.

Unfied Consent feature depends on SyncUserConsentSeparateType feature
as Chromium needs to continue to record and sync user consent when the
user disables event logger (USER_EVENTS sync model type).

This CL also moved the unified_consent feature definition from components/signin
to components/unified_consent. This is the correct code location for the feature
and is also required as it now depends on a sync feature.

Bug: 860433
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I062904486c7c0085b6256b3df5d4ad7edd9ca704
Reviewed-on: https://chromium-review.googlesource.com/1128962
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: vitaliii <vitaliii@chromium.org>
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Commit-Queue: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576209}
35 files changed