Custom path to save a panic report

Currently Report::persist uses env::temp_dir() to get a base folder to save a panic report

    /// Write a file to disk.
    pub fn persist(&self) -> Result<PathBuf, Box<dyn Error + 'static>> {
        let uuid = Uuid::new_v4().hyphenated().to_string();
        let tmp_dir = env::temp_dir();
        let file_name = format!("report-{}.toml", &uuid);
        let file_path = Path::new(&tmp_dir).join(file_name);
        let toml = self.serialize().expect("only using toml-compatible types");
        std::fs::write(&file_path, toml.as_bytes())?;
        Ok(file_path)
    }

However on some platforms TMPDIR may not be defined or be RO (yes, weird but true) . Sure TMPDIR may be overwritten when starting application however it would be nice to configure a base dir either as a parameter to ::handle_dump (breaking change) of through Metadata object

Inizia leggendo Report::persist e i punti di ingresso ::handle_dump e Metadata menzionati nell’issue per capire dove viene selezionata la directory dei report. Decidi come configurare la directory di base, quindi verifica che un report possa essere scritto nella posizione configurata mantenendo il comportamento predefinito esistente.