Wiki sidebar expand/collapse toggle should remain in consistent position on left side

Note: Resolution of this Issue also Closes out Wiki missing menu (#582521)

Summary

The Wiki sidebar expand/collapse icon should be positioned on the left side and remain in the same location whether the sidebar is expanded or collapsed. Currently, the toggle appears in the title area on the right side in both states.

Why This Change Makes Sense

1. Fixed left sidebar: We recently changed the Wiki sidebar to be fixed on the left side (not following content container). Having the toggle on the left aligns with this architectural decision.
2. Spatial proximity: The toggle should be near the sidebar it controls, not in the title area
3. Positional consistency: Users should find the toggle in the same location regardless of sidebar state

Current Behavior

Current: Wiki sidebar collapsed	Current: Wiki sidebar expanded

• Toggle icon appears on the right side near the page title
• Position is the same whether sidebar is collapsed or expanded
• Spatially disconnected from the sidebar it controls

Proposed

Proposed: Wiki sidebar collapsed	Proposed: Wiki sidebar expanded

• Toggle icon should be positioned on the left side, adjacent to the sidebar
• Icon should remain in the same position whether sidebar is collapsed or expanded
• Control stays visually connected to the element it controls