Csv2bufr

Bug fix and default output path

This release provides:
- clearer output from the CLI tool
- default group and user added to the Dockerfile + resulting image.

Bug fixes:
- Empty values in the BUFR templates were not previously detected correctly. This has now been fixed.

This release provides the following updates and breaking changes:

- update to v2.28.0 of ecCodes
- removal of JSON metadata
- simplified mappings
- documentation updates (WMO theming)
- update of `_meta` to be GeoJSON compatible
- cleanup of modules/dependencies
- improved templates
- addition csv2bufr transform as pygeoapi process plugin

This release provides the following updates and breaking changes:

- add extra error logging on station metadata errors
- update message `_meta` to be a GeoJSON
- remove use of JSON station metadata
- use WMO Sphinx theme for docs
- update to json schema for mapping from csv to BUFR.

Bugfix release to align with https://github.com/wmo-im/wis2box/issues/280

Update ecCodes dependency to 2.27. Add missing data/empty string handling