Update Swashbuckle and improve generated OpenAPI files (#6066)

* Improve generated OpenAPI files

* Nullable

* Fmt

* Correct powershell command

* Fix name

* Add some tests

* Fmt

* Switch to using json naming policy

test/SharedWeb.Test/EnumSchemaFilterTest.cs

@@ -0,0 +1,41 @@
+using Bit.SharedWeb.Swagger;
+using Microsoft.OpenApi.Any;
+using Microsoft.OpenApi.Models;
+using Swashbuckle.AspNetCore.SwaggerGen;
+
+namespace SharedWeb.Test;
+
+public class EnumSchemaFilterTest
+{
+    private enum TestEnum
+    {
+        First,
+        Second,
+        Third
+    }
+
+    [Fact]
+    public void SetsEnumVarNamesExtension()
+    {
+        var schema = new OpenApiSchema();
+        var context = new SchemaFilterContext(typeof(TestEnum), null, null, null);
+        var filter = new EnumSchemaFilter();
+        filter.Apply(schema, context);
+
+        Assert.True(schema.Extensions.ContainsKey("x-enum-varnames"));
+        var extensions = schema.Extensions["x-enum-varnames"] as OpenApiArray;
+        Assert.NotNull(extensions);
+        Assert.Equal(["First", "Second", "Third"], extensions.Select(x => ((OpenApiString)x).Value));
+    }
+
+    [Fact]
+    public void DoesNotSetExtensionForNonEnum()
+    {
+        var schema = new OpenApiSchema();
+        var context = new SchemaFilterContext(typeof(string), null, null, null);
+        var filter = new EnumSchemaFilter();
+        filter.Apply(schema, context);
+
+        Assert.False(schema.Extensions.ContainsKey("x-enum-varnames"));
+    }
+}