Support for automatic conversion from JUnit tests to NUnit tests

[paulirwin]

Discussed in #95

^{Originally posted by nzdev December 16, 2023}
Support for automatic conversion from JUnit tests to NUnit tests to help with porting tests.

Initial Analysis

I think we can do this, for the following features:

• Attribute/annotation mapping (i.e. @Test to [Test] is trivial, but also things like @BeforeEach to [SetUp])
• Assertion/assumption mapping. Note that we should probably lean into the new NUnit 4.x Assert.That format rather than ClassicAssert.
• @ValueSource to (many) [TestCase] mapping for parameterized tests