Add Support unit tests for ConcurrentSet

[paulirwin]

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Adds support unit tests for ConcurrentSet

Fixes #1118

Description

As noted in #1118, this type should pass the same tests as ConcurrentSet (apart from the constructor differences). So this PR takes the tests created in #1117 and refactors them out into a base class that can be used for both ConcurrentHashSet and ConcurrentSet test fixtures. The two protected abstract methods are factory methods to create the specific implementation being tested. The two constructor tests that are specific to ConcurrentHashSet only exist on TestConcurrentHashSet.

Additionally, this PR removes a few more usages of SystemTypesHelpers in those shared tests.

[NightOwl888]

I ran the tests on Azure DevOps. There are failures now on every run. Most of these are due to #1123. Could you have a look at that?

• https://dev.azure.com/LuceneNET-Temp/Lucene.NET/_build/results?buildId=2412&view=results
• https://dev.azure.com/lucene-net-temp2/Lucene.NET/_build/results?buildId=1092&view=results
• https://dev.azure.com/lucene-net-temp3/Lucene.NET/_build/results?buildId=896&view=ms.vss-test-web.build-test-results-tab
• https://dev.azure.com/lucene-net-temp4/Main/_build/results?buildId=318&view=ms.vss-test-web.build-test-results-tab

This one is new, but it might be a one-off:

  Passed Lucene.Net.Store.TestDirectory.TestLUCENENET521 [100 ms]
  Passed Lucene.Net.Store.TestDirectory.TestNotDirectory [3 ms]
  Passed Lucene.Net.Store.TestDirectory.TestRAMDirectoryFilter [< 1 ms]
[ERROR] OneTimeTearDown: An exception occurred during CleanupTemporaryFiles() in Lucene.Net.Store.TestDirectory:
System.IO.IOException: Could not remove the following files (in the order of attempts):
   C:\Users\VssAdministrator\AppData\Local\Temp\LuceneTemp\LUCENENET521-ujwvk5d1\_0.cfs
   C:\Users\VssAdministrator\AppData\Local\Temp\LuceneTemp\LUCENENET521-ujwvk5d1\_0.cfx
   C:\Users\VssAdministrator\AppData\Local\Temp\LuceneTemp\LUCENENET521-ujwvk5d1

   at Lucene.Net.Util.TestUtil.Rm(FileSystemInfo[] locations) in /_/src/Lucene.Net.TestFramework/Util/TestUtil.cs:line 66
   at Lucene.Net.Util.LuceneTestCase.CleanupTemporaryFiles() in /_/src/Lucene.Net.TestFramework/Util/LuceneTestCase.cs:line 3172
   at Lucene.Net.Util.LuceneTestCase.OneTimeTearDown() in /_/src/Lucene.Net.TestFramework/Util/LuceneTestCase.cs:line 1039
  Passed Lucene.Net.Store.TestDirectory.TestThreadSafety [7 s]
  Passed Lucene.Net.Store.TestFileSwitchDirectory.TestBasic [164 ms]
  Passed Lucene.Net.Store.TestFileSwitchDirectory.TestCompoundFileAppendTwice [34 ms]

• https://dev.azure.com/shad0962/Experiments/_build/results?buildId=2578&view=results

[NightOwl888]

Given the test failures should now be resolved by #1131, this looks good to merge.