BREAKING: Remove SystemConsole class, #920, #936

[paulirwin]

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Removes the SystemConsole class from Lucene.NET.

Related: #920, #936

Description

#920 had an item for adding unit tests for SystemConsole, but after discussion with @NightOwl888, we determined that this class is not needed in Lucene.NET, and only serves as an unnecessary abstraction. Users that wish to override the Console.Out/Error behavior can use Console.SetOut or Console.SetError to replace them with a different TextWriter. Most of the usage is in tests anyways, and the usage in non-test code is behind VERBOSE flags.

#936 raised an issue with MAUI support, but this was only a problem with Console.In. Console.Out and Console.Error work fine in MAUI.

This is a breaking change because SystemConsole was previously public.

[NightOwl888]

Thanks for the PR.

We can now remove FEATURE_ARGITERATOR, since it only existed in SystemConsole.