[sedax90]

Summary

• Ctrl+E shows the tab shown before this one. Hold Ctrl and press E again to go further back; the tab bar shows where you are. Letting go of Ctrl keeps that tab, Escape goes back to the tab you started on.
• The order covers every session's tabs in the window, drops closed and moved tabs, and puts tabs never shown after the shown ones, in bar order. Tabs passed during a walk are not recorded.
• Ctrl+Shift+O opens the tab overview, as in GNOME Web and Console. Typing searches the tabs by title and connection.
• The walk ends when Ctrl is let go anywhere in the window, a dialog or popover included, when another shortcut runs, or when the window loses focus.
• Ctrl+E is off with one tab, so the key goes on to the editor. View Open Tabs is off with no tab, since the overview cannot open then.
• Ctrl+Tab stays the next tab, as across GNOME.
• Both keys are in the shortcuts dialog.
• Replaces the first version's Recent Tabs dialog and its tab overview menu item: the overview is the stock list of tabs.

Screenshots

Three editor tabs, shown in the order 1, 3, 2.

	Light	Dark
Before: Ctrl+E
After: Ctrl held, E pressed twice
After: Ctrl+Shift+O, typed "query 3"
After: shortcuts dialog

Test plan

• ui::workspace::recent_tabs: recency order, never-shown tabs last, closed tabs dropped, a walk records only where it ends, Escape returns to the start, the window's key controller goes with the shell.
• recent_tabs::tests::real_keys (XTEST): hold Ctrl and press E twice, then let go; Escape mid-walk; Ctrl+T mid-walk; letting go of Ctrl inside a dialog.
• tests::shell::show_tabs_opens_and_closes_the_overview_while_a_tab_is_open, workspace_actions, application::accelerators, tab_view_freed_after_teardown.
• verify.sh build and lint (rustfmt, clippy with and without default features).