Request button on bound with children

[dbranchini]

For context or background information - see #3200.

Summary of problem Currently, there is no option for a user to request a child item from that record view, instead a user has to follow the instructions/note to go to the parent item and then request that item in order to obtain the child item that they're interested in.

Solution Display a request button on child records to make requesting a child item easier for the user.

Related to #4074.

Display request button at the location-level or the item-level on child items of bound withs. Whether it's location-level or item-level is existing logic. It depends on whether it's a pageable location. If it's pageable, then it's displayed at the location-level. If it's not a pageable, then it's displayed at the item-level if the parent item is checked out or unavailable.

From @saseestone on #3200:

From the storytime discussion on 3/4, we decided we needed an example of a Green stacks item with the parent checked out. This will help with testing requests when the request button is at the child item level.

I've checked out this parent record in folio-test: a6290236
Child record associated is: a6290245

If a request is clicked at the location level and there are multiple items, the item selector is displayed after the user decides on whether it's a Request & pickup or Scan & deliver. Whether there's an option for Request & pickup or Scan & deliver is existing logic.
If a request is placed on a child item and either - it's a request at the item level or it's a request at the location level but there's only one item, the request is automatically routed to the parent record.
If a request is placed on a child item that's associated with a specific volume/copy on the parent record, the request is automatically routed to that volume/copy (and not the item selector view).
If a request is placed on a parent item, the request is routed to the parent record. There is no change here, except that additional child details are displayed in the request app.

The request app tickets are sul-dlss/sul-requests#1998 (item selector) or sul-dlss/sul-requests#1446 (single item).

[jcoyne]

Currently blocked by #4074