Paintera-conversion-helper

Changelog
* Use relative paths to N5 container in label-to-block mapping when converting label multiset datasets.
* Allow to use existing `s0` dataset as raw data input to skip conversion and only generate scale levels
* Removed deprecated `paintera-conversion-helper` command in favor of newer `paintera-convert`

Bug fixes
* Fix meshes not showing up in converted label datasets on Windows after converting on Janelia cluster 45
* Fix `NullPointerException` in Gson adapter initialization when running conversion on Janelia cluster 40
* Fix duplicate group name `/data/data/` instead of just `/data/` in label multiset converter

Default to n5 backend for label-block-lookup by default.

New Features
- Consider the `fragment-segment-assignment` of a Paintera dataset when exporting the highest resolution scale level with the `--consider-fragment-segment-assignment` option and add additional assignments with the `--additional-assignment` option.