[15/N] Add DIR_METADATA files to directories under //chrome/app

Generate DIR_METADATA files and remove metadata from OWNERS
files for directories under //chrome/app.

Bug: 1113033
Change-Id: I64518e0abcb696004f8f2c948d2b02198b860144
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2577871Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>
Cr-Commit-Position: refs/heads/master@{#834777}

chrome/app/DIR_METADATA

+monorail:  {
+  component:  "Internals>PlatformIntegration"
+}

chrome/app/OWNERS

-# COMPONENT: Internals>PlatformIntegration
 #
 # For .grd and .grdp changes, TBR an OWNER below. If you are not
 # a google employee then you also need to file a bug in which the

chrome/app/generated_resources_grd/DIR_METADATA

+monorail:  {
+  component:  "Internals>PlatformIntegration"
+}

chrome/app/generated_resources_grd/OWNERS

-# COMPONENT: Internals>PlatformIntegration
 #
 # Any Chromium committer can approve changes to generated_resources.grd,
 # so they are also allowed to approve the corresponding sha1 hashes

chrome/app/media_router_strings_grdp/DIR_METADATA

+monorail:  {
+  component:  "Internals>Cast>UI"
+}

chrome/app/media_router_strings_grdp/OWNERS

 file://chrome/browser/media/router/OWNERS
-
-# COMPONENT: Internals>Cast>UI

chrome/app/nearby_share_strings_grdp/DIR_METADATA

+monorail:  {
+  component:  "UI>Browser>Sharing>Nearby"
+}

chrome/app/nearby_share_strings_grdp/OWNERS

 file://chrome/browser/nearby_sharing/OWNERS
-
-# COMPONENT: UI>Browser>Sharing>Nearby

chrome/app/printing_strings_grdp/DIR_METADATA

+monorail:  {
+  component:  "Internals>Printing"
+}

chrome/app/printing_strings_grdp/OWNERS

 file://printing/OWNERS
-# COMPONENT: Internals>Printing

chrome/app/sharesheet_strings_grdp/DIR_METADATA

+monorail:  {
+  component:  "Platform>Apps>Foundation"
+}

chrome/app/sharesheet_strings_grdp/OWNERS

 file://chrome/browser/sharesheet/OWNERS
-
-# COMPONENT: Platform>Apps>Foundation

chrome/app/vector_icons/webauthn/DIR_METADATA

+team_email:  "identity-dev@chromium.org"

chrome/app/vector_icons/webauthn/OWNERS

 file://device/fido/OWNERS
 
 # Component: Blink>WebAuthentication
-# TEAM: identity-dev@chromium.org