Devscripts::Compression: Switch to new Dpkg::Compression getters

The compression_get_property() function has been deprecated and replaced with specific getters, which are easier to extend. Add backwards compatibility code to ease backporting, and bump the minimum Dpkg::Compression version to the one present in Debian stable.

I had to silence the deprecation warnings temporarily to let dpkg migrate, but I'd like to be able to reenable them so that external users can see them and switch before they get removed.

(BTW the CI failure on unstable seems to be a problem with the recent pylint upload missing a dependency? Will try to check and file a report. I've also got fixes for the other autopkgtest failures with the newer dpkg, to not let xz warn or exit non-zero.)

Closes: #1027718