Initial mapping of brand configs to keys

This will excise the key-mgmt config from the current platform configs
and eventually remove the need to proxy key-id mappings through firmware
signing back through to the signer.

Specifically, this will obsolete:
key-id in cros_config schema
DeviceSignerConfig (which proxies through to key-id)

BUG=None
TEST=None

Change-Id: I952ffbb870c7997740423e66efe06d658e280456
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2414630
Tested-by: C Shapiro <shapiroc@chromium.org>
Reviewed-by: Andrew Lamb <andrewlamb@chromium.org>
Commit-Queue: C Shapiro <shapiroc@chromium.org>
Auto-Submit: C Shapiro <shapiroc@chromium.org>
2 files changed