Add basic authentication in the server (#1670)

* Add basic authentication in the server

A pattern for creating authentication methods is introduced, with three
authentication types defined:
  none - no authentication
  session - like the current session based auth used for user annotations
  test - used to test the login/logout process end to end

The config endpoint now returns informations about the authentication, like if
the user is authenticated and their username.  The redirect uri's for login and
logout are also returned if the authentication type requires login

This is the first a several PRs for authentication.

*. Update server tests to avoid hardcoded ports

test_api and test_nan_rest now use a common function for starting a test server,
than will initially choose a random port.

server/app/app.py

@@ -85,6 +85,7 @@ def dataset_index(url_dataroot=None, dataset=None):
     try:
         cache_manager = current_app.matrix_data_cache_manager
         with cache_manager.data_adaptor(url_dataroot, location, app_config) as data_adaptor:
+            data_adaptor.set_uri_path(f"{url_dataroot}/{dataset}")
             dataset_title = app_config.get_title(data_adaptor)
             return render_template(
                 "index.html", datasetTitle=dataset_title, SCRIPTS=scripts, INLINE_SCRIPTS=inline_scripts
@@ -143,6 +144,7 @@ def rest_get_data_adaptor(func):
     def wrapped_function(self, dataset=None):
         try:
             with get_data_adaptor(self.url_dataroot, dataset) as data_adaptor:
+                data_adaptor.set_uri_path(f"{self.url_dataroot}/{dataset}")
                 return func(self, data_adaptor)
         except DatasetAccessError as e:
             return common_rest.abort_and_log(
@@ -160,6 +162,17 @@ def dataroot_test_index():
 
     config = current_app.app_config
     server_config = config.server_config
+
+    auth = server_config.auth
+    if auth.is_valid():
+        if server_config.auth.is_authenticated():
+            data += f"<p>Logged in as {auth.get_userid()} / {auth.get_username()}</p>"
+        if auth.requires_client_login():
+            if server_config.auth.is_authenticated():
+                data += "<p><a href='/logout'>Logout</a></p>"
+            else:
+                data += "<p><a href='/login'>Login</a></p>"
+
     datasets = []
     for dataroot_dict in server_config.multi_dataset__dataroot.values():
         dataroot = dataroot_dict["dataroot"]
@@ -338,10 +351,15 @@ class Server:
                     lambda dataset, url_dataroot=url_dataroot: dataset_index(url_dataroot, dataset),
                     methods=["GET"],
                 )
+
         else:
             bp_api = Blueprint("api", __name__, url_prefix=api_version)
             resources = get_api_resources(bp_api)
             self.app.register_blueprint(resources.blueprint)
 
+        self.app.auth = server_config.auth
+        if self.app.auth.requires_client_login():
+            self.app.auth.add_url_rules(self.app)
+
         self.app.matrix_data_cache_manager = server_config.matrix_data_cache_manager
         self.app.app_config = app_config