Xml doc to description conversion

The following usage:

```csharp
class MyTestClass
{
///
/// The description of the test method.
///
[Test]
public void MyTest()
{
/* ... */
}
}
```

should be equivalent to

```csharp
class MyTestClass
{
[Test]
[AllureDescription("The description of the test method.")]
public void MyTest()
{
/* ... */
}
}
```

#### Considerations

- [ ] Explore the possibility of getting a test method's xml documentation
- [ ] Implement doc-to-string conversion

Start by investigating how the C# test integration exposes test methods and whether their XML documentation is available at runtime. Explore the two checklist items, then verify the conversion with a focused test based on the shown MyTest example; done means its report description matches the text.

Written by the indexing model from the issue text.