Implement support for C#10

[cranberry-clockworks]

Looks like the formatter doesn't support C#10 features.

For example:

// test1.cs
using System;

namespace Foo;

class Bar {
}

$ ./prettysharp.exe test1.cs
[line 3] Error at ';': Expected '{' at the beginning of a namespace declaration

The file with the older namespace style works just fine:

// test2.cs
using System;

namespace Foo {
    class Bar {
    }
}

$ ./prettysharp.exe test1.cs
using System;

namespace Foo
{
    class Bar
    {

    }
}