Fix for the Issue: #1330

Fixed for given nested value classes when relaxed mocking is enabled then value successfully verified.
Added couple of test(s) so that it will be verified in every PR.

Root Cause
Because of this PR's: https://github.com/mockk/mockk/pull/1314/files change in the below code in the else part, this issue was broken. Instead of returning this in the else block which returns the value class, instead check if there is any boxedValue and return the same if exists else return the same value class.

Earlier

return if (resultType == expectedReturnType && !(isReturnNullable && isPrimitive)) {
    this.boxedValue
} else {
    this
}

Now

return if (resultType == expectedReturnType && !(isReturnNullable && isPrimitive)) {
    this.boxedValue
 } else {
    this.boxedValue ?: this
 }