Update test projects to properly build and run under dotnet7

Source/Engine/Tests/TestStringUtils.cs

@@ -0,0 +1,26 @@
+// Copyright (c) 2012-2023 Wojciech Figat. All rights reserved.
+
+using NUnit.Framework;
+
+namespace FlaxEngine.Tests
+{
+    /// <summary>
+    /// Tests for <see cref="StringUtils"/>.
+    /// </summary>
+    [TestFixture]
+    public class TestStringUtils
+    {
+        /// <summary>
+        /// Test incrementing name numbers.
+        /// </summary>
+        [Test]
+        public void TestIncName()
+        {
+            Assert.AreEqual("my Name", StringUtils.IncrementNameNumber("my Name", null));
+            Assert.AreEqual("my Name", StringUtils.IncrementNameNumber("my Name", x => true));
+            Assert.AreEqual("my Name 10", StringUtils.IncrementNameNumber("my Name 1", x => x.EndsWith("10")));
+            Assert.AreEqual("my Name (10)", StringUtils.IncrementNameNumber("my Name (1)", x => x.EndsWith("10)")));
+            Assert.AreEqual("my Name110", StringUtils.IncrementNameNumber("my Name100", x => x.EndsWith("110")));
+        }
+    }
+}