Adding the feature to Enable posting private comments by internal user

Hi Spenser,
Please take a look at the addCommentSection.js controller.
When adding comment the post call was missing the 'isDraft' method parameter, not sure how it was working, but have added the correct strataService method signature.

strataService.cases.comments.post() had 3 parameters, but the controller call had only 2. I have further added 'isPublic' parameter to it.

Have tested successfully with internal & customer user :)