rust: Improve Host/Install speed

rust: Improve Host/Install speed

* Compress dist archives with gzip instead of xz; gzip is faster to
  compress and decompress

* Use a for loop instead of calling find to extract archives

* Use libdeflate's gzip to decompress instead of gzip

* Limit search for install scripts to top level of extracted archives

This also runs the install scripts with bash instead of sh, in
accordance with the shebang lines inside the scripts.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>