Improve Emoji import (fix #15429) (#15430)

* Improve Emoji import

Skip macOS '._' shadow files in tar archive to speed up import

* Fix codeclimate format issue with whitespace

* Update lib/mastodon/emoji_cli.rb

suggestions from Gargron to improve comment

Co-authored-by: Eugen Rochko <eugen@zeonfederated.com>

* Update emoji_cli.rb

Remove extraneous comment (macOS-specific comment now with correct line)

Co-authored-by: Eugen Rochko <eugen@zeonfederated.com>

lib/mastodon/emoji_cli.rb

@@ -43,7 +43,12 @@ module Mastodon
         tar.each do |entry|
           next unless entry.file? && entry.full_name.end_with?('.png')
 
-          shortcode    = [options[:prefix], File.basename(entry.full_name, '.*'), options[:suffix]].compact.join
+          filename = File.basename(entry.full_name, '.*')
+
+          # Skip macOS shadow files
+          next if filename.start_with?('._')
+
+          shortcode    = [options[:prefix], filename, options[:suffix]].compact.join
           custom_emoji = CustomEmoji.local.find_by(shortcode: shortcode)
 
           if custom_emoji && !options[:overwrite]