Tests inside extensions are not listed correctly when parsing LSP test requests

The follow code should generate two TestItems inside another

```swift
final class MyTests: XCTestCase {
    func test1() {
    }
}

extension MyTests {
    func test2() {
    }
}
```
In the TestExplorer you should get something like this
```
- MyTests
  - test1()
  - test2()
```

Currently they are getting listed as
```
- MyTests
  - test1()
- test2()
```
