Option for extra newline on autocorrection of ValidSigil

[maxveldink]

When autocorrecting the Sorbet/ValidSigil cop on files without any magic string comments at the top, it adds the sigil without an extra newline like so:

# typed: false
class Banana
...

This generally trips the Layout/EmptyLineAfterMagicComment cop and a subsequent auto correct needs to be run. This is okay locally, but can be annoying in CI when we're using a tool like Pronto to make suggestions; we need to run the job again to pick up this difference.

It would be great to introduce an option to this cop to insert an extra blank line when it adds the magic string up top. I can imagine some teams would not like that behavior, but an option seems reasonable.

Would love some thoughts on this, or if I'm missing an easy way around this issue. I'll work on a PR soon to implement the option.