add --loglevel commandline argument for logging

remove the progressbar for extension installation in favor of logging output

modules/logging_config.py

@@ -0,0 +1,16 @@
+import os
+import logging
+
+
+def setup_logging(loglevel):
+    if loglevel is None:
+        loglevel = os.environ.get("SD_WEBUI_LOG_LEVEL")
+
+    if loglevel:
+        log_level = getattr(logging, loglevel.upper(), None) or logging.INFO
+        logging.basicConfig(
+            level=log_level,
+            format='%(asctime)s %(levelname)s [%(name)s] %(message)s',
+            datefmt='%Y-%m-%d %H:%M:%S',
+        )
+