Change Toolbar format from browser style to ribbon style in DB editor

[nelliputkonen]

See subitems in issue #2492 (https://github.com/spine-tools/Spine-Toolbox/issues/2492) under titles "Top menu and Toolbar" and "Hamburger menu (in Toolbar)".

So to summarize: Get rid of hamburger menu and bring to ribbon style like in Workflow editor. The address line can also go to header similar to Workflow editor. Maintain tabs, but add Commit, Purge, Undo (fix to actually 'undo' from current 'back'), Redo (the same as 'undo'), 'Graph/Table/Pivot view toggle' and 'Reset views' . Remove 'Open database in project' icon, but maintain "+" in tabs. Toolbox logo links to github page. From hamburger menu items, move 'User guide' under Help menu item and Settings under File or Edit.