Copy multiple tabs when they're selected and "Copy selection" is clicked

[wheelercj]

Although there is a "Copy multiple tabs" button in the popup that copies links for all selected tabs, the "Copy selection" button would be more intuitive if it did that too. (The "Copy multiple tabs" button does other things too; this will be the only overlap in functionality between the two buttons.)

The "Copy selection" button cannot request the tabs permission necessary for this feature because permission requests cannot be made after detecting whether multiple tabs are selected, so the user will have to click the "Copy multiple tabs" button at least once (and grant the tabs permission) before this feature can be used.