Checkin: Add Pieces for a Purchase Order Line with newly added Item through plugin

Purpose: Users need to be able to Checkin items that have been ordered on a PO Line so that they can keep track of whether or not they have received everything they ordered.

Scenario 1:
Add Piece
Given each checkin record (piece) will relate to a PO Line
And each check-in record will have a "title", "Piece Caption", "Expected Date", and "Status".
Add item while adding piece
Given the user is adding item records for each piece on the POL
When adding piece
Then display "Add item" button
Adding item details
Given the user is adding item details while adding a piece
When user clicks "add item' button
Then Create/edit item modal displays
see screenshot - Note: this is intended to load the inventory item form in a modal
User clicks Add Piece or Check-in button in Add Piece modal and Piece is added or checked-in.

Acceptance criteria:

• inventory Item is created through Add Item button/plugin modal and piece could be saved or checked-in with relation to added item;

Note: A PO Line should allow for multiple titles (IF it is for a package) to be associated with it through Checkin (Add Title) - This will be necessary to accommodate the existence of "Container records" in inventory once they have been implemented and the ability to create a "Container" through PO Line, see UXPROD-1105.

• Objects in inventory will be created at the point of "Checkin Record" (Piece) creation and they will be updated at the point of Checkin for each Piece