Support key bindings to add row/column in table

[Spenhouet]

In Confluence you can use the following key bindings to create new rows/columns in tables:

• CTRL + ALT + ↑: Insert row above the currently selected cell
• CTRL + ALT + ↓: Insert row below the currently selected cell
• CTRL + ALT + ←: Insert column left of the currently selected cell
• CTRL + ALT + →: Insert column right of the currently selected cell

This makes editing tables really nice.
I wish Milkdown would support these key bindings.