Bug 11466: improve selection of item types for purchase order desired format list

This patch ensures that the list of desired formats for a purchase
suggestion includes the list of item types so long as the
AdvancedSearchTypes system preference includes 'itemtypes'.

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-- Synopsis --
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When system preference AdvancedSearchTypes has other values than 'itemtypes',
for ex 'itemtypes|loc', itemtypes selection in opac-suggestions.pl
is not populated with available itemtypes.

This patch fixes the issue by broadening the strict comparison of
($advanced_search_types eg 'itemtypes') #fails 'itemtypes|loc'
to
($advanced_search_types =~ 'itemtypes') #succeeds 'itemtypes|loc'

Unit tests included

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-- Test plan --
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REPLICATING THE ISSUE
1. Set system preference  AdvancedSearchTypes to itemtypes|loc
2. Go to opac-suggestions.pl and observe Item type <select> dropdown list
2.1. List should have only the default value

AFTER APPLYING THIS PATCH
1. Set system preference  AdvancedSearchTypes to itemtypes|loc
2. Go to opac-suggestions.pl and observe Item type <select> dropdown list
2.1. List should have itemtypes available for selection

Signed-off-by: Nicole C. Engard <nengard@bywatersolutions.com>
Tests worked as expected. Placed a suggestion and saw the whole
list of item types, chose one, saved, checked staff and it loaded
as expected. Changed item type in staff and it applied in both
views.

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Works as described, passes all tests including new regression tests.
Restores old functionality.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 11466: (follow-up) add additional test

This adds an additional test case to document the behavior
that if AdvancedSearchTypes contains 'itemtypes' or /is/
'itemtypes', that it returns the same results.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>