adds code injection admin frontend implementation, handlebar helpers + settings

escaping handlebars
Code Injection - adds perms, shortcuts, icon, flag

refs #1993

- adds ctrl/cmd+s for save
- adds config flag
- adds icon on settings page, puts items in the right order
- sorts out permissions for all settings pages with consistent configuration
Merge pull request #4578 from ErisDS/pr-3489

Code Injection PR 3489 rebased and updated