[Upload] Component specs

[aweell]

Story description

• Drag-and-drop functionality is not working when adding new files for the first time
• Rethink component layout and sizes
• Rethink component states and upload process flow

[3.6.0] Updates

• Component draft waiting for revision

Related tasks

• [Upload] Color specs update #310
• [Upload] Update component documentation to new template #428
• [Upload] Images update #429
• [Upload] Update UI-Kit component #431