[18.0][ADD] purchase_order_etd_eta

[AungKoKoLin1997]

The module adds ETD, ETA, and Shipping Schedule Note fields to purchase orders and displays them in the purchase order and RFQ reports.

@qrtl QT6348

[yostashiro]

Please add CONTEXT.md to explain in what situations the provided functionality is useful.

[nobuQuartile]

It’s a small detail, but I’d appreciate it if you could take a look.

Functional test: Done
Purchase Order Fields
Confirmed that ETD, ETA, and Shipping Schedule Note can be set and saved on Purchase Orders.
Search and Filters
Verified search, date filters, and group by for ETD, ETA, and Shipping Schedule Note.
List Views
Checked that ETD, ETA, and Shipping Schedule Note are available in list and KPI views.
Reports
Verified ETD, ETA, and Shipping Schedule Note appear correctly in RFQ and PO reports.
Expected Arrival Setting
Confirmed Expected Arrival is hidden in reports when the setting is enabled and ETA is set.