Enable/disable Fabric multitasking context carry across browser tabs

We're improving Fabric's multitasking experience by giving users control over how context behaves when they open Fabric in another browser tab. Today, open items, tab order, pinned items, and tab groups automatically carry over to additional tabs in the same browser profile. While this supports continuity and multitasking, customer feedback indicates that some users prefer a clean workspace for separate tasks and that inherited items can contribute to reaching the 20-open-item limit.We're planning a user-selectable setting that lets users choose whether a new Fabric browser tab continues their existing context or opens with a clean context