move cli functions to its own class

Author: joshedney

tools/fastlane-plugin/lib/fastlane/plugin/bugsnag/actions/bugsnag_cli.rb

@@ -12,7 +12,7 @@ def self.get_bugsnag_cli_path(params)
       bugsnag_cli_version = Gem::Version.new(`#{bugsnag_cli_path} --version`.scan(/(?:\d+\.?){3}/).first)
 
       if bugsnag_cli_version < bundled_bugsnag_cli_version
-        UI.warning("Your bugsnag-cli is outdated. The current bugsnag-cli version is: #{bundled_bugsnag_cli_version}")
+        FastlaneCore::UI.warning("Your bugsnag-cli is outdated. The current bugsnag-cli version is: #{bundled_bugsnag_cli_version}")
       end
       bugsnag_cli_path
     else