refactor config to support different config options for datasets in different dataroots. (#1596)

This will give us the ability to specify different config options for
different dataroots.

the key of the dataroot dictionary is no longer the same as the dataroot_url.
Previously key==dataroot_url, and now those are separated.

Added an "is_multi_dataset" function to simplify logic where it branched on single vs multi.

Simplified the rest.py interface by no longer passing in the user annotations object, since
that can be retrieved from the dataset.

server/test/test_eb.py

@@ -0,0 +1,54 @@
+import unittest
+import tempfile
+import requests
+import subprocess
+from server.test import PROJECT_ROOT
+from server.common.app_config import AppConfig
+from contextlib import contextmanager
+import time
+
+
+@contextmanager
+def run_eb_app(tempdirname):
+    ps = subprocess.Popen(["python", "artifact.dir/application.py"], cwd=tempdirname)
+    server = "http://localhost:5000"
+    for _ in range(10):
+        try:
+            requests.get(f"{server}/health")
+            break
+        except requests.exceptions.ConnectionError:
+            time.sleep(1)
+
+    try:
+        yield server
+    finally:
+        try:
+            ps.terminate()
+        except ProcessLookupError:
+            pass
+
+
+class Elastic_Beanstalk_Test(unittest.TestCase):
+    def test_run(self):
+
+        tempdir = tempfile.TemporaryDirectory(dir=f"{PROJECT_ROOT}/server")
+        tempdirname = tempdir.name
+
+        c = AppConfig()
+        # test that eb works
+        c.update_server_config(
+            multi_dataset__dataroot=f"{PROJECT_ROOT}/server/test/test_datasets", app__flask_secret_key="open sesame"
+        )
+
+        c.complete_config()
+        c.write_config(f"{tempdirname}/config.yaml")
+
+        subprocess.check_call(f"git ls-files . | cpio -pdm {tempdirname}", cwd=f"{PROJECT_ROOT}/server/eb", shell=True)
+        subprocess.check_call(["make", "build"], cwd=tempdirname)
+
+        with run_eb_app(tempdirname) as server:
+            session = requests.Session()
+
+            r = session.get(f"{server}/d/pbmc3k.cxg/api/v0.2/config")
+            data_config = r.json()
+            assert data_config["config"]["displayNames"]["dataset"] == "pbmc3k"