Introduce a single "adjust security" toolbar button for security slider and noscript options
Right now, the security slider is buried under a submenu. We could promote it to its own toolbar buttun/popup menu, similar to how ninavizz suggested in #21183 (moved). And we could move needed NoScript functionality (namely "temporarily whitelist video/audio/scripts for this tab") from the NoScript dropdown to the security popup. Other dangerous NoScript functionality could be omitted altogether (including "Allow Scripts Global" and "Options".
Finally the security slider button could have a decoration that indicates the current setting "H/M/L" as well as a second indicator showing whether we have temporarily whitelisted for this tab.