Support -F with --stdin

[alex-shinn]

Expected Behavior

It's reasonable to want to use ktlint as a filter, reading Kotlin code on stdin and writing the correctly formatted version to stdout. Many other auto-formatters work this way, and it's important to be able to call out to ktlint from editors like Emacs and vim.

The separately reported issue to allow a --path=... with --stdin would complement this well.

Current Behavior

ktlint -F --stdin produces no output.

Additional information

• Current version of ktlint: 0.46.1

[paul-dingemans]

Duplicate of #1153. Specifically, see #1153 (comment)

[alex-shinn]

Thanks! Sorry for the duplicate.