Arch & Artix already have the `libarchive` pkg, which contains `bsdtar`.
So lets just use it, since its superior, faster, it also has easier syntax, and it auto-detects the compression.
btw the .tar.zst was wrong anyhow, so if u wont merge this, dont forget to fix that. from the manual:
```
-I, --use-compress-program=COMMAND
Filter data through COMMAND. It must accept the -d option, for decompression. The argument can contain command line options.
.....
--zstd Filter the archive through zstd(1).
```
This is a re-attempt of #643
- `[ "$archive" = "" ]` may be replaced with `[ -z "$archive" ]`
- added exit codes
- upon entering `ext -c` with no arguments stderr will be thrown
from readlink, should be suppressed
