✨ feat(cli): add config file support

- load configuration from a file
- use config crate for config loading
- allow overriding config with environment variables
- set default credential path
- fix error handling for config loading

src/error.rs

@@ -45,4 +45,7 @@ pub enum Error {
     /// Error from toml_de
     #[error(transparent)]
     TomlDe(#[from] toml::de::Error),
+    /// Error from config
+    #[error(transparent)]
+    Config(#[from] config::ConfigError),
 }