Angular <eg-patron-search> search org should be sticky

[Jane Sandberg]

The angular patron search can be found in the staff catalog's Place Hold screen. Its Search Org field could use two improvements to its behavior, inspired by the Angularjs version:

* Bug 1691264 - adds a workstation setting called eg.circ.patron.search.ou to make this org selector sticky. This has been very useful to our staff (many of our staff search at the system level, rather than at their workstation org). It would be great to use that same workstation setting so that staff-preferred OUs come over to Angular.

* Bug 1721131 - right now, the Angular Clear Form button always switches the org selector back to the root org. It should not change the org unit (i.e. the staff member's selected ou should persist through clicking "Clear Form")

[Bill Erickson (berick)]

Note bug #1889113 adds persistence support to eg-org-select.

[Jane Sandberg (sandbergja)]

Here's a branch that provides this behavior: user/sandbergja/lp1891960_sticky_ou_patron_search

Note that the Angularjs patron search org field is storing its settings in the browser, rather than the database, so I didn't attempt any migration of those values. Staff members will have to set their desired search org separately in Angular (which shouldn't be much of a hassle).

Testing notes from the commit message:
1) Find a title in the staff catalog.
2) Click Place Hold.
3) Search for a Patron.
4) Notice that the search org is initially
your root org (Consortium-level).
5) Select a different value.
6) Leave and come back to this screen. Note
that the value you selected remains.
7) Perform a search to make sure that the
search is limited to the org you selected.
8) Click the Clear button. Note that the
value you selected still remains.
9) Perform another search to make sure that the
search is limited to the org you selected.

[Bill Erickson (berick)]

Works great. Thanks, Jane. Merged to master for 3.6