that we need to adjust to. OpenRA update the language version to 7.3,
which seems to not compile with our mono/msbuild combination, hence
downgrade to 7.2 and re-work one part of the code that relies on 7.3
semantics. OpenRA now depends on nuget, so there's a new distfile that
contains the nuget dependencies. Furthermore, add a workaround for the
dllmap config files.
Committing on behalf of thfr@
Tested by and ok bket@ tobhe@
Tested by patrick@ on arm64
Tested by thfr@
7179983490