Rework authentication file path
From @jonas comment:
> https://forum.duniter.org/t/call-for-testing-silkaj-v0-10-0rc/9187/2
### `authentication` command
- [x] Drop default `./authfile` file path
- [x] Save v1 auth file as user readable `600` `rw-------` mode, not group and world readable
- [x] Change to be done in DuniterPy: duniterpy#203+
- Solved with DuniterPy v1.2 bump
### Authentication
- [x] The authentication should stop reading default `./authfile`
---
- [ ] Store and read authentication files into common place:
- [Implement XDG Secret Service guideline](https://www.freedesktop.org/wiki/Specifications/secret-storage-spec/)
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