Don't allow to change campaign start or end date beyond first action

[groganz]

• [x] Restrict duration hook as per first/last action
• [ ] Restrict timespan hook as per first/last action
• [x] Check before persisting whether meanwhile new action has been created which is first/last
• [ ] Implement all checks for modals in timeline as well and have modal display warning
• [ ] For Scheduled Campaign
• [ ] For Repeating Campaign
• [ ] For Campaign Templates
• [ ] Change date in duration hook to new start or end limit after warning was shown