improve proxy functionality and configuration

src/config/utils.rs

@@ -0,0 +1,8 @@
+use std::io;
+
+pub fn generate_toml_parser_error_in_field(field: &str) -> io::Error {
+    io::Error::new(
+        io::ErrorKind::InvalidData,
+        format!("Invalid format for config.toml in {} field", field),
+    )
+}