Revert to tabs in "New look" | Tabs sidebar takes too much real estate

[dibaccin1]

Horizontal real estate in reports is already an issue in the PowerBI service due to filters sidebar. The "new look" introduces a new sidebar and moves the tabs into this sidebar. This is causing issues with the experience for our customers. Because of the new sidebar the reports are now sized down and cannot be seen in projectors. Tabs should be reverted back to the bottom to match the way other Microsoft products like Excel behave.