Bug 23808: Pre-fill guarantor fields when adding guarantee to guarantor

Bug 23808: Pre-fill guarantor fields when adding guarantee to guarantor

Bug 14570 removed the guarantor pre-fill functionality when selecting
'Add guarantee' to an Adult patron. This is because guarantor
information would now only display if (1) the patron record exists
(which it won't when first adding guarantee to guarantor record) and (2)
if there is already a guarantor added to a guarantee

This patchfix will pre-fill guarantor fields and address fields (so the guarantee
has the same address as the guarantor) if no relationship (existing
guarantor data exists) and a guarantor_id is handed to memberenty.pl in
URL when clicking 'Add guarantee' button on Adults patron record.

Test plan:
1. Add adult patron make sure to fill in their 'Main address' details
2. Select 'Add guarantee'
3. Observe no details of the adult patron are displaying in the
   'Guarantor information' section or 'Main address' sections of memberentry.pl
4. Select 'Search to add', search for your adult patron and choose
  'Select' to add them as guarantor
5. Fill out rest of memberentry.pl and 'Save'
6. Observe adult is showing as the guarantor
7. Apply patch
8. Run tests:
   sudo koha-shell <instancename>
   prove xt
   prove t
9. Confirm tests pass
10. Return to your adult patron
11. Select 'Add guarantee'
12. Observe in 'Guarantor information' and 'Main address' sections of
    memberentry.pl are pre-filled with the 'patron #' (borrowernumber),
    surname, firstname and street number, address, address2 (if you
    filled that in on adults account), city
13. Fill out the rest of memberenty.pl and save and confirm your adult
    patron is showing as the guarantor and the pre-filled address details
    have been saved and are showing
14. Repeat steps 10,11 and 12 and in the 'Guarantor information' select
    'Search to add' and add another adult as guarantor
15. Fill out the rest of memberentry.pl and 'Save' and notice with this
    patch applied you can still add multiple guarantors successfully

Sponsored-by: South Taranaki District Council, NZ
Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: George Veranis <gveranis@dataly.gr>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>