feat(ui): Adding manifest prefix config (#19141)

* Adding manifest prefix config

* Fixing broken tests

* Fixing import

* Adding prefix for remaining assets

* Changing static prefix strategy

* Fixing DST test

* Fixing up formatting

* Fixing up async_query_manager.py types

tests/unit_tests/extension_tests.py

@@ -0,0 +1,51 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from os.path import dirname
+from unittest.mock import Mock
+
+from superset.extensions import UIManifestProcessor
+
+APP_DIR = f"{dirname(__file__)}/fixtures"
+
+
+def test_get_manifest_with_prefix():
+    app = Mock(
+        config={"STATIC_ASSETS_PREFIX": "https://cool.url/here"},
+        template_context_processors={None: []},
+    )
+    manifest_processor = UIManifestProcessor(APP_DIR)
+    manifest_processor.init_app(app)
+    manifest = manifest_processor.get_manifest()
+    assert manifest["js_manifest"]("main") == ["/static/dist/main-js.js"]
+    assert manifest["css_manifest"]("main") == ["/static/dist/main-css.css"]
+    assert manifest["js_manifest"]("styles") == ["/static/dist/styles-js.js"]
+    assert manifest["css_manifest"]("styles") == []
+    assert manifest["assets_prefix"] == "https://cool.url/here"
+
+
+def test_get_manifest_no_prefix():
+    app = Mock(
+        config={"STATIC_ASSETS_PREFIX": ""}, template_context_processors={None: []}
+    )
+    manifest_processor = UIManifestProcessor(APP_DIR)
+    manifest_processor.init_app(app)
+    manifest = manifest_processor.get_manifest()
+    assert manifest["js_manifest"]("main") == ["/static/dist/main-js.js"]
+    assert manifest["css_manifest"]("main") == ["/static/dist/main-css.css"]
+    assert manifest["js_manifest"]("styles") == ["/static/dist/styles-js.js"]
+    assert manifest["css_manifest"]("styles") == []
+    assert manifest["assets_prefix"] == ""