[16.0][FIX] pos_stock_available_online: stock move updates

[danielduqma]

Make stock updates not only on quant updates, but also when a stock move changes its state.

This fixes two bugs:

• Stock is not updated when a new incoming move is ready, or when a ready one is cancelled. This triggers notification in both outgoing and incoming warehouses

• Stock is decreased twice because when quant is updated, move is taken in account because it is not yet on 'done' state. This was reported in https://github.com/OCA/pos/issues/1039, but the proposed solution in https://github.com/OCA/pos/pull/1041 was local and only concerned moves from PoS orders

FL-556-4139