Ignore --format option when running in LSP mode

[searls]

The LSP depends on using the base formatter, because printing to STDOUT will break any LSP (since that's the communication channel back to the host). This is a recent regression: standardrb/vscode-standard-ruby#26 (comment)

Make sure this can't be overridden by user settings: https://github.com/standardrb/standard/blob/main/lib/standard/lsp/stdin_rubocop_runner.rb#L15

[searls]

Fixed in 1.39.1