S allius/issue395 (#399)

* add button for languages setting

* build a web module for the dashboard

- load all python module from local dir
- initialize Blueprint and Babel

* set a default key for secure cookies

* add translations to docker container

* improve translation build  

- clean target erases the *.pot
- don't modify the resurt of url_for() calls
- don't translate the language description

* translate connection table, fix icon

* build relative urls for HA ingress

* fix unit test, increase coverage

app/src/utils/__init__.py

@@ -0,0 +1,25 @@
+import mimetypes
+from importlib import import_module
+from pathlib import Path
+from collections.abc import Callable
+
+
+class SourceFileLoader:
+    """ Represents a SouceFileLoader (__loader__)"""
+    name: str
+    get_resource_reader: Callable
+
+
+def load_modules(loader: SourceFileLoader):
+    """Load the entire modules from a SourceFileLoader (__loader__)"""
+    pkg = loader.name
+    for load in loader.get_resource_reader().contents():
+
+        if "python" not in str(mimetypes.guess_type(load)[0]):
+            continue
+
+        mod = Path(load).stem
+        if mod == "__init__":
+            continue
+
+        import_module(pkg + "." + mod, pkg)