Restyle default tooltips and toast notifications

[lukaw3d]

Before	After

Adds a solid background and removes the shadow to be consistent with SidebarTooltip

[github-actions]

🦙 MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ EDITORCONFIG	editorconfig-checker	1		0	0.01s
✅ REPOSITORY	checkov	yes		no	13.54s
✅ REPOSITORY	git_diff	yes		no	0.01s
✅ TSX	eslint	1	0	0	5.13s

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[csillag]

Shouldn't we do something similar about the notifications, too? The shadow / elevation seems to be an overkill.

[csillag]

The change is OK.
(It would be nice adjust Notification, too, but from a cursory look of the available settings, I'm not sure it's trivially possible.)

[lukaw3d]

Good reminder!