A simple way to indent multi-line strings

A simple way to indent multi-line strings
I suggest to qute each line, and use no more sympols, like this:
```VB.NET
Dim multiline =
"Class Test"
" Dim x As Integer"
" Dim Y As Integer"
"End Class"
```

Today, this will not compile, so it will not break any thing. All VB should do, is to compile it to:
```VB.NET
Dim multiline =
"Class Test
Dim x As Integer
Dim Y As Integer
End Class"
```

Note:
I have another proposal to add indents in the editor itself:
https://github.com/dotnet/roslyn/issues/34006
but this one here is just in case the other one didn't happen.