Validate inferred time zone offsets

[ericpohl]

There are two places in the code where we infer the timezone offset vs. UTC by comparing DateTime values - a UTC value in a SpatialRecord, presumably from the GPS, and a local value from the monitor. We then use this timezone offset to compute DateTimeOffset values in SpatialRecordMapper.ToUtc().

We were seeing data come in from the field in which the inferred timezone offset was 19 hours, which raised an ArgumentOutOfRangeException in the DateTimeOffset constructor:

{System.ArgumentOutOfRangeException: Offset must be within plus or minus 14 hours. (Parameter 'offset')
   at System.DateTimeOffset.ValidateOffset(TimeSpan offset)
   at System.DateTimeOffset..ctor(Int32 year, Int32 month, Int32 day, Int32 hour, Int32 minute, Int32 second, Int32 millisecond, TimeSpan offset)
   at AgGateway.ADAPT.ISOv4Plugin.Mappers.SpatialRecordMapper.ToUtc(DateTime dateTime, Nullable`1 timezoneOffset)
   at AgGateway.ADAPT.ISOv4Plugin.Mappers.SpatialRecordMapper.GovernsTimestamp(ISOProductAllocation p, SpatialRecord spatialRecord)
   at AgGateway.ADAPT.ISOv4Plugin.Mappers.SpatialRecordMapper.<>c__DisplayClass11_0.<SetNumericMeterValue>b__1(ISOProductAllocation p)
   at AgGateway.ADAPT.ISOv4Plugin.Mappers.SpatialRecordMapper.SetNumericMeterValue(ISOSpatialRow isoSpatialRow, NumericWorkingData meter, SpatialRecord spatialRecord, Dictionary`2 productAllocations)
   at AgGateway.ADAPT.ISOv4Plugin.Mappers.SpatialRecordMapper.Map(ISOSpatialRow isoSpatialRow, List`1 meters, Dictionary`2 productAllocations)
   at AgGateway.ADAPT.ISOv4Plugin.Mappers.SpatialRecordMapper.<>c__DisplayClass8_0.<Map>b__0(ISOSpatialRow r)

It appears that the monitor had the date set one day ahead (24 hours ahead minus 5 hour timezone offset = 19 hours). There is no reliable way to fix this data that I am aware of, so instead of throwing away the entire dataset, simply null out the timezone offset, record an error, and proceed as best we can.

An additional change is to add the .vscode subdirectory to .gitignore, as this contains user-specific data for Visual Studio Code.

[kelly-nelson]

Looks good to me. @strhea ?

[strhea]

Agreed.