Add section for protocol specific information on the admin page (#4910)

This PR adds section for protocol specific information, then always show
both of OStatus and ActivityPub. Specifically, this will help admins to
check PuSH subscription status and unsubscribe manually, even `protocol`
has been changed.

This also includes below changes:

* Add `overflow: hidden` to prevent float leaking
* Add missing fields for ActivityPub

config/locales/en.yml

@@ -60,6 +60,7 @@ en:
       email: E-mail
       feed_url: Feed URL
       followers: Followers
+      followers_url: Followers URL
       follows: Follows
       inbox_url: Inbox URL
       ip: IP
@@ -93,6 +94,7 @@ en:
       resubscribe: Resubscribe
       salmon_url: Salmon URL
       search: Search
+      shared_inbox_url: Shared Inbox URL
       show:
         created_reports: Reports created by this account
         report: report