Display the types of unequal items in collections

[bradwilson]

(Adapted from #2452)

When two items appear equal but are not because of type differences, the assertion message shows this type difference:

Assert.Equal<object>(3, 3L);

Assert.Equal() Failure
Expected: 3 (System.Int32)
Actual:   3 (System.Int64)

However, when the two items in question are in a collection, the message shows the position but no type information:

Assert.Equal(new object[] { 1, 2, 3 }, new object[] { 1, 2, 3L });

Assert.Equal() Failure
                 ↓ (pos 2)
Expected: [1, 2, 3]
Actual:   [1, 2, 3]
                 ↑ (pos 2)

I'm guessing this is probably the best output format (but I'm open to other suggestions):

Assert.Equal() Failure
                 ↓ (pos 2, type System.Int32)
Expected: [1, 2, 3]
Actual:   [1, 2, 3]
                 ↑ (pos 2, type System.Int64)

We only want the type to be printed when the types don't match; so unequal values with the same type should print like this:

Assert.Equal() Failure
                 ↓ (pos 2)
Expected: [1, 2, 3]
Actual:   [1, 2, 4]
                 ↑ (pos 2)

not this:

Assert.Equal() Failure
                 ↓ (pos 2, type System.Int32)
Expected: [1, 2, 3]
Actual:   [1, 2, 4]
                 ↑ (pos 2, type System.Int32)

[mongeon]

I'm going to grab this one and make it happen ;)