Bug 25019: Make the ViewPolicy filter initialization standard

Bug 25019: Make the ViewPolicy filter initialization standard

This patch makes the ViewPolicy filter use the 'params' accessor instead
of relying of ->{options} which has no accessor. This will allow
interacting with the filter object be similar through all the filters in
the chain.

To test, we just need to verify no behaviour change takes place:
1. Run:
   $ kshell
  k$ prove t/db_dependent/Filter_MARC_ViewPolicy.t
=> SUCCESS: Tests pass
2. Apply this patch
3. Repeat 1
=> SUCCESS: Tests still pass!
4. Sign off :-D

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>