Fixes#8783
Our new tab flow will never have a previously focused window because its
triggered by a service so we need to use the "preferred parent" logic we
have to open this in the last focused window.
First, remove the always-inlined openTerminalFromPasteboard code and
combine it with openTerminal. Now that we're doing a bit of work inside
openTerminal, there's little better to having an intermediate, inlined
function.
Second, combine some type-casting operations (saving a .map() call).
Lastly, adjust some variable names because a generic `objs` or `urls`
was a little ambiguous now that we're all in one function scope.
