feat: add file logging (#2023)

logs into `lnbits.log` with info loglevel and `debug.log` with DEBUG loglevel
files will be saved into `LNBITS_DATA_DIR`.
retentions is configurable but defaults to `90 days`
* added log rotation aswell

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Co-authored-by: Vlad Stan <stan.v.vlad@gmail.com>

lnbits/server.py

@@ -37,6 +37,7 @@ def main(
 
     # create data dir if it does not exist
     Path(settings.lnbits_data_folder).mkdir(parents=True, exist_ok=True)
+    Path(settings.lnbits_data_folder, "logs").mkdir(parents=True, exist_ok=True)
 
     # create `extensions`` dir if it does not exist
     Path(settings.lnbits_extensions_path, "extensions").mkdir(