[FIX] web_editor: shift paste of vs code content looses indentation

Before this commit:

when performing a shift paste of copied VS Code content, the indentation was
lost.

After this commit:

Now, when you perform a shift paste of copied VS Code content, the indentation
is preserved

Task-2884491

closes odoo/odoo#122828

Signed-off-by: David Monjoie (dmo) <dmo@odoo.com>