Unblacklist Windows 1903/1909 (with new-enough Docker Engine)

[TBBle]

Per docker/for-win#4100 (comment), Docker 19.03.6 contains the work-around for the Windows HCS issue that prevents larger-than-default container sizes in the Windows 1903/1909 kernel.

I've tested the workaround on my desktop machine at home, but not with ue4-docker, as my ue4-docker build host at work is ltsc2019. I see no reason why it wouldn't work in ue4-docker though...

So we could remove the blacklisting of those base versions, and either check or document that the Docker version in-use is new-enough to have that fix, similarly for the original 8GB-file issue.

That is assuming I'm correct that the 1903/1909 black-listing is because of the storage-opts bug... If it was something else, disregard this. ^_^

[adamrehn]

Excellent, running ue4-docker diagnostics maxsize on my machine with Windows 10 version 1909 and Docker Engine 19.03.8 shows the diagnostic passing successfully. Commit with an updated check incoming...

[adamrehn]

Fix is live in ue4-docker version 0.0.65, but I forgot to update the lookup table to include the 1903 and 1909 base image tags, so it's actually usable in ue4-docker version 0.0.66, which also includes a fix for a broken download link the prerequisites image, as reported in #82.