Lucene.Net.TestFramework: Fixed random seed functionality so it is repeatable (Fixes #288)

[NightOwl888]

NOTE: This PR should be squashed.

Fixes #288.

These changes are still experimental, have had minimal manual testing, and don't have any automated tests. But, the need to repeat a test failure outweighs the need to make these features stable before merging them, IMHO.

Features

• Random Seed Reporting - Upon a test failure, the random seed, random culture, and instructions on how to apply it are appended to the test message.
• Test Fixture Wrapping - We add an extra outer nested test fixture to capture all of the OneTimeSetUp and OneTimeTearDown calls before the first test and after the last test in the fixture.
• LuceneTestCase.TestFixtureAttribute - A copy of NUnit's attribute, modified with some extra hooks to setup our test framework.
• LuceneRandomSeedInitializer - Determines whether to use a random seed or one from the current context to initialize the seeds for each test fixture/test. Also registers the RandomizedContext for each test fixture/test.
• RandomizedContext - A static class that is registered as an NUnit test property, which allows us to use strongly-typed properties for RandomSeed (the initial seed), TestSeed, CurrentTestAssembly, and of course the RandomGenerator for the context.
• LuceneTestCase.SetUpFixture - An internal class that captures all OneTimeSetUp and OneTimeTearDown calls from our "wrapper" test fixture and uses reference counting to ensure we always call LuceneTestFrameworkInitializer (or a subclass of it) exactly 1 time before the first test is run and after the last test is run.
• NUnitTestFixtureBuilder - A copy of the class with the same name from NUnit, with the extra bits to inject the random seeds and take the filters out of the equation so the random generator gets the exact same number of calls regardless of which filters are applied. It also manages the assembly-level RandomizedContext instance, which is applied as a property to every "wrapper" test fixture.
• RandomSeedAttribute - An assembly-level attribute that can be used to apply a random seed that was reported as a failure to repeat the results. It is also possible to set the random seed in a .runsettings file in the solution directory or a lucene.testsettings.json file in any directory in the path of the test assembly.
• UseTempLineDocsFileAttribute - An assembly-level or class-level attribute that specifies to unzip the LineFileDocs to a temp directory one time per assembly, so it doesn't have to be repeated in each test. This feature only works if the file has a .gz extension. The path to the unzipped file is available from the LuceneTestCase.TestLineDocsFile property. To specify an external LineFileDocs file, use the tests:linedocsfile system property (which works from .runsettings or from lucene.testsettings.json).
• NUnit.Framework.SetCultureAttribute - This attribute can be used to override the randomly generated culture. Or it can be set in .runsettings/lucene.testsettings.json using the key tests:culture and the value of the culture (such as fr-CA).

Breaking Changes

• An Initialize() virtual method was added to LuceneTestFrameworkInitializer, which is where the properties CodecFactory, DocValuesFormatFactory, PostingsFormatFactory, and ConfigurationFactory must be set. An InvalidOperationException will be thrown if they are set in the constructor, TestFrameworkSetUp() or TestFrameworkTearDown().
• StringHelper.GOOD_FAST_HASH_SEED has been turned into a static property and renamed to StringHelper.GoodFastHashSeed (the seed is also a setting that is set to a fixed value during repeatable testing).
• LuceneTestCase.GetTestClass() was deprecated and changed into a new property TestType.
• AbstractBeforeAfterRule.Before() and AbstractBeforeAfterRule.After() methods have had their LuceneTestCase parameter removed.

This PR also includes some plumbing to generate the source code to build a SynonymMap, so it can be quickly reconstituted for a non-random test (for internal debugging purposes).

The [AwaitsFix] attribute has been applied to the remaining test failures, and the azure-pipelines.yml is now set to fail the build if we get more than 0 test failures (previously this was set to 2).

References

• https://get-testy.com/tag/nunit/
• https://docs.microsoft.com/en-us/visualstudio/test/configure-unit-tests-by-using-a-dot-runsettings-file