Refactor czi_hosted and server into backend directory, pull common code into backend/common, refactor tests (#2102)

* move local_server -> backend/server server-> backend/czi_hosted, pull common code into backend/common update imports, tests and make commands

backend/test/test_server/locust/config.py

@@ -0,0 +1,15 @@
+"""
+Locust test config
+"""
+
+
+""" Data routes that will be tested """
+
+# single dataset, for non-dataroot tests
+# DataSets = [""]
+
+# multi-dataset, for dataroot tests.  these are varied in size/shape
+DataSets = [
+    "GSE60361.cxg",
+    "WongAdultRetina.cxg",
+]