[MIR] fonts-liberation2

The package has been available in universe since 17.10, it is architecture-independent, and it is synced from Debian.

It is recommended by libreoffice and libreoffice-common since version 6.0 (see bug #1732950).

Security:
 - there are no known past or present security vulnerabilities for the package
 - the package doesn't install binaries, nor services/daemons, and doesn't open ports, it only installs ttf files under /usr/share/fonts/truetype/liberation2/

Quality assurance:
 - the package doesn't ask debconf questions when installed
 - there are no bug reports for the package in Debian (https://bugs.debian.org/cgi-bin/pkgreport.cgi?dist=unstable;package=fonts-liberation2) and Ubuntu (https://bugs.launchpad.net/ubuntu/+source/fonts-liberation2)
 - as should be expected with a font package, all the upstream bug reports are about missing or incorrectly rendered glyphs (https://pagure.io/liberation-fonts/issues)
 - the package is well maintained in Debian (by the Debian Fonts Task Force)
 - there are no Ubuntu-specific changes, the package is synced as-is from Debian
 - there is nothing hardware-specific in the package
 - the package uses a debian/watch file
 - the package doesn't rely on obsolete packages

Dependencies: the package doesn't have any runtime dependencies.

Standards compliance: the packaging is trivial, and meets the Debian Policy standards as far as I can tell.

Maintenance: there is no designated owning team in Ubuntu, is this required given that the package is synced from Debian?