Bug 28634: Fix notice borrowernumber

Bug 28634: Fix notice borrowernumber

This commit fixes the bug described in this bug.

- When a partner is selected, pass their borrowernumber rather than email to the
receiving script
- Iterate all selected partners, send a notice to each, using the
recipient's borrowernumber in the notice, the recipient's email is
derived from their patron object

TEST PLAN:
1. DO NOT apply the patch.
2. Follow the following setup:

*** Setup start ***
- Create a report using the following SQL in order to verify that
notices are being generated:
SELECT borrowernumber, subject, content, message_transport_type,
to_address, from_address FROM message_queue WHERE letter_code LIKE
'ILL%' ORDER BY message_id DESC

- Create two "partners". These are patrons that belong to a
patron category that has a code that matches the <partner_code> value in
your koha-conf.xml (default is ILLLIBS). Patrons in this category must
have a primary email defined. Patrons defined in this way are offered as
request partners within the ILL interface.

- Go to "Koha administration", search for "ILLModule" syspref, ensure it
is set to "Enable"
- Go to "Koha administration", search for "IllLog" syspref, ensure it is
set to "Log"

BRANCH CONFIG
- Go to "Koha administration" > "Libraries"
- Choose a library and "Edit" it
- Ensure the "Email" field for the library is populated

SENDING REQUEST TO PARTNERS
- Go to the "Manage ILL request" screen for a request, create a request
if one does not exist
- Choose "Place request with partners"
- Select both partners that were defined earlier, then click
"Send email"
- Run the report created earlier
=> TEST: Observe that a notice was created and the borrowernumber is
that of the request creator, not the recipient
*** Setup end ***

3. Apply the patch
a. Go to the "Manage ILL request" screen for a request, create a request
if one does not exist
b. Choose "Place request with partners"
c. Select both partners that were defined earlier, then click
"Send email"
d. Run the report created earlier
=> TEST: Observe that once notice per partner is created, the
borrowernumber column for each notice contains the borrower number of
the recipient, not the request creator

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>