Do not store temporary directories in the Dangerzone's config directory.
There are two reasons for that:
1. They are ephemeral, and they need a temporary place to be stored,
preferably RAM-backed.
2. We need to set them while running our CI tests.
Allow users to disable timeouts via the CLI, with the
`--disable-timeouts` argument. By default, the timeouts are always
enabled.
This option applies both to the CLI version of Dangerzone, and the GUI
one. For the latter, the user must start the GUI from their CLI (i.e.,
`dangerzone --disable-timeouts ...`)