Improve styling of interactive components

[#41475421]
Add custom parameters and sliders to control pairwise sigma / epsilon

[#41834627]
Set custom pairwise LJ props in custom-lj-props MML for elements 2-3

[#41834627]
Convert custom pairwise LJ properties from MML to JSON

[#41834627]
Update MML conversion tests (new array - pairwiseLJProperties)

[#41834627]
Add a new MML test to check custom LJ properties conversion

[#41834627]