Feature/7.x/multiple custom menus
Make custom menus in CP specific to MSM sites; https://github.com/ExpressionEngine/ExpressionEngine/discussions/3572
Allow multiple custom menus per role; https://github.com/ExpressionEngine/ExpressionEngine/discussions/3572 Display custom menu heading in navigation; https://github.com/ExpressionEngine/ExpressionEngine/discussions/3646 Use icons for the add-ons in sidebar custom menus; #2859 Deprecate ee()->menu legacy library
closes #3270 closes #4922
This initially seemed like a small change, but turned out into changing how models are related etc, so we can only do it in 7.5
Needs to have tests written
Wondering if we might want to call the Menu something for reference, but actually display another Heading. eg. "Client's Menu"... but displayed Heading could be "Quick Edits"