Added value class support

[LarsSven]

This MR serves to add support for value classes to Mockito Kotlin. Value classes currently break and there is no easy way around them, many users have had issues with this: #445

This MR adds an anyValueClass() and adds it to the any() and anyOrNull() implementation. I expect I may have done a few things non-optimally as I am not too familiar with Mockito's inner workings, but I look forward to feedback from someone who knows more about Mockito argument matchers than me to help me improve this. I do think it is important to get support for value classes.

[TimvdLippe]

Not sure why, but tests are failing on this PR. Can you please take a look and ensure all tests are passing?

[LarsSven]

I resolved the issues with the tests, it was a relatively obscure issue that had to do with verify not being called for the test where we expected it to error out. I also went ahead and added more tests to test other scenarios like around null vs non-null and nested value classes.

[TimvdLippe]

Awesome, thanks for the fix!

[vans239]

Is there any plan to add support for eq function?

We use snippet below currently, so it should work for eq also

inline fun <reified T> eqValue(v: T): T {
    val field = T::class.java.declaredFields.first { !Modifier.isStatic(it.modifiers) }.apply { isAccessible = true }
    val method = T::class.java.getDeclaredMethod("box-impl", field.type).apply { isAccessible = true }
    return method.invoke(null, ArgumentMatchers.eq(field.get(v))) as T
}