Make TimeZone changeable

[masaedw]

TimeZone used by os.time () is hard coded in TimeZoneInfo.LocalTime, but by applying this pull request, it can be changed for each Script object.

ex)

Script S = new Script();
// set your preferred TimeZoneInfo
S.Options.LocalTimeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById("Central European Standard Time");
// You can get local time different from the system time zone
DynValue res = S.DoString("return os.date(\"%Y-%m-%d %H:%M:%S\")");

[LimpingNinja]

Sorry for the delay, we've got new maintainers now and are culling the backlog.

[LimpingNinja]

Logic needs to be added to:

src/MoonSharp.Interpreter/_Projects/MoonSharp.Interpreter.netcore/src/CoreLib/OsTimeModule.cs
src/Unity/MoonSharp/Assets/Plugins/MoonSharp/Interpreter/CoreLib/OsTimeModule.cs

If adding this in to the current system; as we push to clean this up it will change, but for now this PR will be accepted if the additional locations are updated.