Enable more compression methods for Zarr datasets

[normanrz]

The PR #627 brings initial support for Zarr in the Dataset API. One major limitation is that only Blosc+Zstd compression is enabled. It would be desirable to enable a larger variety of compression methods that are already implemented for Zarr (cf. numcodecs). I wouldn't allow all compression methods, but limit the available compression methods to the ones that webKnossos can actually read.