Ensure that newline is inserted after file scoped namespace declarations

[Inurias]

Fixes #65921
Closes #67400

[Inurias]

@dotnet-policy-service agree

[Inurias]

There are some tests failing that have code like this in their expected string:

namespace ConsoleApp185;
using System;
using System.Collections.Generic;

which would now be:

namespace ConsoleApp185;

using System;
using System.Collections.Generic;

How should these cases be handled? Do I update the expected strings in those tests?

[CyrusNajmabadi]

o I update the expected strings in those tests?

Yup. We can review all the changes and make sure it matches our expectations. Thanks!

[Inurias]

o I update the expected strings in those tests?

Yup. We can review all the changes and make sure it matches our expectations. Thanks!

Done :)

[Inurias]

@CyrusNajmabadi is there anything else to do here?

[CyrusNajmabadi]

Nope. Looks great. Thanks for the ping and for the contribution!