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/settings.py

@@ -296,6 +296,9 @@ class EnvSettings(LNbitsSettings):
     lnbits_extensions_path: str = Field(default="lnbits")
     super_user: str = Field(default="")
     version: str = Field(default="0.0.0")
+    enable_log_to_file: bool = Field(default=True)
+    log_rotation: str = Field(default="100 MB")
+    log_retention: str = Field(default="3 months")
 
     @property
     def has_default_extension_path(self) -> bool: