Update icons in "New" menu

[juliusknorr]

we aim to have the icons updated for v29, the remaining parts can be ignored or implemented given the 29-timebox

Part of nextcloud/server#44340

• Document: description in #49abea
• Spreadsheet: file-table-box in #9abd4e
• Presentation: file-presentation-box in #f0965f
• Diagram: drawing-box in #ebc94a

Before	After