Display reCAPTCHA modal when making issue public

What does this MR do?

Display a reCAPTCHA dialog if an issue is detected as spam while making it public.

see #28542 (closed)

Screenshots

Screen_Recording_2019-09-30_at_15.33.20

Testing manually

Apply this change to mark all issues as spam:

diff --git a/app/services/spam_service.rb b/app/services/spam_service.rb
index babe69cfdc8..e7a7899c69a 100644
--- a/app/services/spam_service.rb
+++ b/app/services/spam_service.rb
@@ -48,7 +48,7 @@ class SpamService
   def check(api)
     return false unless request && check_for_spam?

-    return false unless akismet.spam?
+    # return false unless akismet.spam?

     create_spam_log(api)
     true