Make update non-optional

[einarmo]

When we added support for "updating" metadata in CDF, it was done in a very flexible way.

Now that we write to DM more, it really makes a lot less sense, since depending on where you write there is no way to not update. We had some absolutely insane code to enable "updates" to Raw that can also be removed (no other extractors do anything like that).

In general, making updates non-optional greatly simplifies the extractor, and is almost certainly what pretty much every user wants.

Also identifies and fixes a bug related to the Source of arrays, this was never caught due to a hole in a test.

[codecov]

Codecov Report

Attention: Patch coverage is 87.75510% with 12 lines in your changes missing coverage. Please review.

Please upload report for BASE (v3-dev@f5fac9b). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
Extractor/Nodes/UAVariable.cs	58.33%	3 Missing and 2 partials ⚠️
Extractor/Nodes/UAVariableType.cs	50.00%	1 Missing and 1 partial ⚠️
Extractor/Pushers/PusherUtils.cs	93.75%	0 Missing and 2 partials ⚠️
Extractor/Nodes/BaseUANode.cs	93.33%	0 Missing and 1 partial ⚠️
Extractor/Nodes/UAObject.cs	66.66%	0 Missing and 1 partial ⚠️
Extractor/Pushers/Writers/CDFWriter.cs	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             v3-dev     #767   +/-   ##
=========================================
  Coverage          ?   80.09%           
=========================================
  Files             ?      125           
  Lines             ?    16380           
  Branches          ?     2396           
=========================================
  Hits              ?    13119           
  Misses            ?     2537           
  Partials          ?      724           

Files with missing lines	Coverage Δ
Extractor/Config/ExtractionConfig.cs	85.52% <ø> (ø)
Extractor/NodeSources/NodeHierarchyBuilder.cs	88.23% <100.00%> (ø)
Extractor/NodeSources/UANodeSource.cs	88.80% <ø> (ø)
Extractor/Pushers/CDFPusher.cs	81.44% <ø> (ø)
Extractor/Pushers/IPusher.cs	40.00% <ø> (ø)
Extractor/Pushers/Writers/BaseTimeseriesWriter.cs	87.87% <100.00%> (ø)
Extractor/Pushers/Writers/CleanWriter.cs	89.14% <100.00%> (ø)
Extractor/Pushers/Writers/IdmWriter.cs	32.77% <ø> (ø)
...tractor/Pushers/Writers/MinimalTimeseriesWriter.cs	90.90% <ø> (ø)
Extractor/Pushers/Writers/RawWriter.cs	93.93% <100.00%> (ø)
... and 10 more