Show current license usage when updating Kentik license of a router

We now showcase the amount of devices already using this license, and the max amount of devices that can be assigned to it

requested review from @mohammad.torkashvand

assigned to @karel.vanklink

approved this merge request

added 4 commits

• ec8a92eb...25dd000e - 3 commits from branch develop
• 65e88e3d - Show current license usage when updating Kentik license of a router

Compare with previous version

enabled an automatic merge when all merge checks for 65e88e3d pass

merged