Libarchive 3.3.3 was released on Sept. 4. and added support for the Zstandard compression filter. This compression method was designed to give similar compression ratio as gzip but with much greater (de)compression speeds. Libarchive uses the libzstd.so library, but seems to use the zstd binary as fallback if it wasn't built with libzstd.
This diff enables the filter in the libarchive plugin. There is still no mimetype in shared-mime-info, so a custom mimetype for zstd-compressed tar archives is added. This necessitated re-adding functionality in Ark for custom mime-types (was removed in commit 73cd5e8d2e7b347d84438b23afdc892eddb78ed2).
Arch linux already added libarchive 3.3.3 and I think most distros should have packaged this version by December, so should be ok to bump the dep version?
This is my first commit in a long while, so please check I didn't forget something ;)
There's a bugreport for adding application/zstd mimetype to shared-mime-info. Maybe we should add one for application/x-zstd-compressed-tar?