Make Claro the default admin theme (#660)

Author: balsama

README.md

@@ -114,6 +114,10 @@ Please use the [Drupal.org issue queue][issue_queue] for latest information and
 to request features or bug fixes.
 
 ## Known Issues
+* There are a few known issues when using the Claro administrative theme with
+  various Lightning components.
+  See https://github.com/acquia/lightning/pull/660#pullrequestreview-331654008
+  for more information.
 
 ### Media
 * If you upload an image into an image field using the new image browser, you

composer.json

@@ -5,6 +5,7 @@
     "license": "GPL-2.0-or-later",
     "require": {
         "ext-dom": "*",
+        "cweagans/composer-patches": "^1.6",
         "drupal/core": "~8.8.0",
         "drupal/lightning_api": "^4.4",
         "drupal/lightning_core": "^5.0",
@@ -57,6 +58,11 @@
         ],
         "patchLevel": {
             "drupal/core": "-p2"
+        },
+        "patches": {
+            "drupal/core": {
+                "3096566 - Copy media library styles from Seven to Claro & 3096241 - Refactor image and file field widgets to improve contrib compatibility and to make their templates and preprocess functions DRY": "https://www.drupal.org/files/issues/2019-12-16/3096566-23-combined-3096241-3.patch"
+            }
         }
     },
     "autoload": {