Create desks_storage component

The desks storage component contains code necessary for saving user's
desk as desk templates to Chrome Sync and loading desk templates from
Chrome Sync and enterprise policy.

This component will be used in:

* chrome/browser/chromeos/extensions for capturing and loading desks
through the Desks Private API go/crosprivatedeskapi.
* ash/wm/desks for accessing saved desk templates.

Bug: 1177413
Change-Id: I4f04422a6bcb888ca31797c4216589bb7291ef3b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2829939
Reviewed-by: Cait Phillips <caitkp@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Yanzhu Du <yzd@google.com>
Cr-Commit-Position: refs/heads/master@{#874841}

components/desks_storage/OWNERS

@@ -0,0 +1,5 @@
+afakhry@chromium.org
+avynn@google.com
+richui@google.com
+xdai@chromium.org
+yzd@google.com

components/desks_storage/README.md

@@ -0,0 +1,3 @@
+The desks storage component contains code necessary for saving user's
+desk as desk templates to Chrome Sync and loading desk templates from
+Chrome Sync and enterprise policy.