settings: Add move_messages_within_stream_limit_seconds element in UI.

This commit adds dropdown for move_messages_within_stream_limit_seconds
setting which is used to control for how long the user is allowed to
edit topic.

tools/lib/capitalization.py

@@ -125,6 +125,8 @@ IGNORED_PHRASES = [
     r"he/him",
     r"she/her",
     r"they/them",
+    # Used in message-move-time-limit setting label
+    r"does not apply to moderators and administrators",
 ]
 
 # Sort regexes in descending order of their lengths. As a result, the