Improve CSP warning modal

The following discussion from !200891 (closed) should be addressed:

• @aturinske started a discussion: (+2 comments)

  Also, in the message, it says To prevent performance issues, this setting will be locked for 10 minutes after making changes.; that timer will have to be on the backend to prevent users from simply refreshing the page to get around a timer on the frontend

Implementation

• backend add 10min timer when a user changes the CSP and prevent a user from making a change during that time
• backend pass up a flag saying whether a user can change the CSP or not
• frontend add a warning in the message
• frontend disable the CSP dropdown if the backend timer is not complete