Enforced validation

Implementation of enforce validation:
- edit project page/edit project version page: maintainer to choose validation rules they want to apply
- 3 new states -
                 Default view in Editor    |    Can toggle by user in editor?    
Off          |  Turn off                        | Yes
Warninig |  Turn on                        | Yes
Error       |  Turn on                        | No

If there's validation error(Validation with 'Error' state):
- In translation when user try to save as 'Translated' in editor, a warning popup will appear.
- When TM Merge and Search & Replace, translation update will be ignore and return warning messages.
- When upload translation via WebUI or REST, translation update will be ignore and return warning messages