Add sdo_write_array method to bulk-configure SDOs

[jamwaffles]

Also handles indexing and setting the SDO length automatically, preventing a common mistake

// New:
subdevice
    .sdo_write_array(0x1c13, &[0x1a00u16, 0x1a02, 0x1a04, 0x1a06])
    .await?;

// Equivalent to:
subdevice.sdo_write(0x1c13, 0, 0u8).await?;
subdevice.sdo_write(0x1c13, 1, 0x1a00u16).await?;
subdevice.sdo_write(0x1c13, 2, 0x1a02u16).await?;
subdevice.sdo_write(0x1c13, 3, 0x1a04u16).await?;
subdevice.sdo_write(0x1c13, 4, 0x1a06u16).await?;
subdevice.sdo_write(0x1c13, 0, 4u8).await?;