[ADD] purchase_stock_ux: mass cancellation of remaining qty to receive

[jcadhoc]

What

Adds a wizard to cancel the remaining quantity to receive on all lines of one or more purchase orders in a single operation.

• New transient model purchase.order.cancel.remaining (+ form with confirmation).
• Exposed as a contextual action ("Mass cancellation of remaining quantities") bound to purchase.order, available from the list and form action menu.
• It collects the order lines whose receipt_status is pending or partial and applies the existing per-line button_cancel_remaining().

Why

There was no way to cancel only the remaining qty to receive of a PO when a vendor delivers partially and the rest won't arrive — the order stayed open indefinitely or had to be cancelled and recreated. The per-line button_cancel_remaining already existed; this adds the order-level (mass) counterpart, mirroring sale.order.cancel.remaining in sale_stock_ux.

Out of scope: remaining qty to invoice (only qty to receive is handled).

How it works

Reuses button_cancel_remaining(), which sets the line product_qty to qty_received + qty_returned; Odoo then cancels the pending moves. Lines already fully received are ignored, and each cancelled line is logged in the chatter.

Test plan

1. Confirm a PO with several lines.
2. Receive one line partially, leave the rest pending.
3. Order action menu → Mass cancellation of remaining quantities → Confirm.
4. Expected: all lines with remaining go to receipt_status = full (ordered qty drops to received qty), pending receptions are cancelled, and the chatter logs the qty change per line. Already-received and already-invoiced quantities are untouched.

Task 52215.

[roboadhoc]