`filewriter`: journals

The file-writing infrastructure must be able to write entries into the instrument `journal.xml` (and into the instrument journal MySQL database, `journal_` MS teams channels, and various other 'journal' workflows)

This is intentionally phrased as

> file-writing infrastructure

as this may not belong in the filewriter itself, but in a separate cooperating process.

See also https://github.com/ISISComputingGroup/DataStreaming/issues/11

## Potential differences from existing files

Not all fields in the current `journal.xml` make sense in the streaming system, for example:
- `icp_version`; this could be populated with a filewriter version instead.
- `detector_table_file` does not exist in the streaming system. Suggest populating this entry with `UNSPECIFIED` or similar.
- `spectra_table_file` / `wiring_table_file` do not have the same meanings/formats/locations in the streaming system. Programs which expect to be able to read a specific format from the filepaths in these entries will fail.

Start by reviewing the related DataStreaming issue 11 and the existing instrument journal.xml structure. Compare its fields with the streaming system, especially icp_version, detector_table_file, spectra_table_file, and wiring_table_file. Done requires an agreed design for writing journals to XML, the journal_ MySQL database, MS Teams channels, and other journal workflows.

Vom Indexierungsmodell aus dem Issue-Text verfasst.