[UI issue] improvement to script manager variables editor

[P6g9YHK6]

Is your feature request related to a problem? Please describe.
editing/adding a big number/long variables can be a pain the ass as you cannot add them in bluk or edit the existing ones

Describe the solution you'd like
when pasting a bulk of data in a field treat line returns as new variables to allow pasting numerous vars

for exemple pasting this into the field:

version={{agent.version}}
operating_system={{agent.operating_system}}
plat={{agent.plat}}
hostname={{agent.hostname}}
local_ips={{agent.local_ips}}

should make 5 variables

when clicking on an existing var allow editing the var to avoid having to delete and recreate it

Describe alternatives you've considered
nothing