Use obj is Array instead of obj.GetType().IsArray

[RenderMichael]

This change has a tiny (but consistent) performance boost, and more importantly improves readability.

This should function exactly the same. Type.IsArray differs only in edge cases which can never be hit by a Type returned by GetType() (the Array type, interfaces, etc).

Benchmark code

using BenchmarkDotNet.Attributes;

namespace NUnit.Framework;

#pragma warning disable SA1010 // Opening square brackets should be spaced correctly

[MemoryDiagnoser(false)]
public class ArrayEqualsBenchmarks
{
    [Benchmark]
    public void AssertStringsEqual()
    {
        string[] actual = ["one", "two", "three"];
        string[] expected = ["one", "two", "three"];
        Assert.That(actual, Is.EqualTo(expected));
    }

    [Benchmark]
    public void AssertStringsEqualFalse()
    {
        string[] actual = ["one", "two", "three"];
        string[] expected = ["one", "two", "four"];
        Assert.That(actual, Is.Not.EqualTo(expected));
    }

    [Benchmark]
    public void AssertIntsEqual()
    {
        int[] actual = [1, 2, 3];
        int[] expected = [1, 2, 3];
        Assert.That(actual, Is.EqualTo(expected));
    }

    [Benchmark]
    public void AssertIntsEqualFalse()
    {
        int[] actual = [1, 2, 3];
        int[] expected = [1, 2, 4];
        Assert.That(actual, Is.Not.EqualTo(expected));
    }
}

Before:

Method	Mean	Error	StdDev	Allocated
AssertStringsEqual	300.4 ns	4.64 ns	4.34 ns	728 B
AssertStringsEqualFalse	604.3 ns	11.58 ns	10.83 ns	1488 B
AssertIntsEqual	930.9 ns	12.96 ns	10.82 ns	1024 B
AssertIntsEqualFalse	1,214.0 ns	9.94 ns	8.30 ns	1776 B

After:

Method	Mean	Error	StdDev	Allocated
AssertStringsEqual	294.7 ns	3.86 ns	3.61 ns	728 B
AssertStringsEqualFalse	595.9 ns	6.70 ns	5.94 ns	1488 B
AssertIntsEqual	915.7 ns	13.69 ns	12.81 ns	1024 B
AssertIntsEqualFalse	1,193.5 ns	8.26 ns	6.90 ns	1776 B

[manfred-brands]

Nice and clean.