add docker build for admin

util/Setup/DockerComposeBuilder.cs

@@ -145,6 +145,16 @@ services:
       - global.env
       - ../env/global.override.env
 
+  admin:
+    image: bitwarden/admin:{CoreVersion}
+    container_name: bitwarden-admin
+    restart: always
+    volumes:
+      - ../core:/etc/bitwarden/core
+    env_file:
+      - global.env
+      - ../env/global.override.env
+
   icons:
     image: bitwarden/icons:{CoreVersion}
     container_name: bitwarden-icons

util/Setup/NginxConfigBuilder.cs

@@ -193,6 +193,10 @@ server {{
   location /icons/ {{
     proxy_pass http://icons/;
   }}
+
+  location /admin/ {{
+    proxy_pass http://admin/;
+  }}
 }}");
             }
         }