Imported form KInfoCenter along with test case. This also includes a
license change from GPL to LGPL.
When working on Linux-centric software it may be necessary to get specific
information about the system beyond what may be obtained from QSysInfo.
This new class allows complete access to all information in the os-release
file as per the os-release "specification".
https://www.freedesktop.org/software/systemd/man/os-release.html