Support JUnit step property

Please support JUnit step property.

See: https://github.com/testmoapp/junitxml?tab=readme-ov-file#steps

Example
```xml

```

I want an option to make 't.Run' to be steps under each test cases.

### Expected Behavior
```go
func Test(t *testing.T) {
t.Run("A", func(t *testing.T) {}
t.Run("B", func(t *testing.T) {}
t.Run("C", func(t *testing.T) {
t.Run("D", func(t *testing.T) {}
}
}
```

generates

```xml

```

No repository files, tests, or entry points are named. Start by tracing how gotestsum converts Go test results into JUnit XML, then inspect how nested t.Run results are represented; done means an option produces the requested step properties and preserves nested names such as C/D.

Written by the indexing model from the issue text.