Styling updates after artist feedback

This feedback came from either krita artists or IRC. These are the following minor style things that are changed:

1. Toolbar in Fusion style now has no border
2. New hamburger menu updated for drop-down options
3. wrap around mode toolbar button is now a highlight button so you know when it is active
4. Vertical separators around symmetry toolbar buttons have been removed
5. Tab close button on open document is a more respectable size
6. Add a bit of padding around table columns. This was worse on Fusion than Breeze style.
7. Converted a few QPushButtons to QToolButtons for button icons so the hover effect works (see gradient chooser)

Here is what it looks like with the changes.

Test Plan

Start Krita and it looks like these changes have been done

Formalities Checklist

• I confirmed this builds.
• I confirmed Krita ran and the relevant functions work.
• I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
• I made sure my commits build individually and have good descriptions as per KDE guidelines.
• I made sure my code conforms to the standards set in the HACKING file.
• I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per KDE Licensing Policy.