added support for GATEWAY_EXTRA_SCRIPTS

cellxgene_gateway/extra_scripts.py

@@ -7,10 +7,11 @@
 # OR CONDITIONS OF ANY KIND, either express or implied. See the License for
 # the specific language governing permissions and limitations under the License.
 
+from cellxgene_gateway import env
 
 def get_extra_scripts():
     # can be array of script tags to inject on every page, e.g. for google analytics could be
     # ['https://www.googletagmanager.com/gtag/js?id=UA-123456-2',
     #  f"{env.gateway_protocol}://{env.gateway_host}/static/js/google_ua.js"]
     # where google_ua.js is a script you add to the static/js folder prior to deployment.
-    return []
+    return [] if env.extra_scripts is None else [p.strip() for p in env.extra_scripts.split(",") if len(p.strip()) > 0]