qga-win: Adding support for Windows Server 2019 get-osinfo command

qga-win: Adding support for Windows Server 2019 get-osinfo command

Since Windows Server 2016, Microsoft stopped upgrading the major and minor
versions of their new Windows Server product, so, the current functionality
of checking major and minor version numbers to determine the Windows Server
version wont work as expected.
The implemented solution here is to use the build number in addition to the
major and minor version numbers of the product to determine the Windows
Server product version.
The final build number of Windows Server 2016 is 14939, and
the final build number of Windows Server 2019 is 17764, so any Windows
Server product that has the major version of 10 and minor version of 0
with a build number lower or equal to 14939 will resemble 2016 and if the
build number is lower or equal to 17763 will resemble 2019.

Reference:
https://techcommunity.microsoft.com/t5/Windows-Server-Insiders/Windows-Server-2019-version-info/m-p/293112/highlight/true#M859

Signed-off-by: Bishara AbuHattoum <bishara@daynix.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>