Bug 8218 : Add a maintenance script to sanitize biblio records

This patch adds:
- a new maintenance script batch_sanitize_records
- a new subroutine C4::Charset::SanitizeRecord
- new unit tests for the new subroutine

Test plan:
1/ prove t/db_dependent/Charset.t
2/ Create a record containing "&amp;amp;" (could be follow with as many
'amp;' as you want) in one of its fields and the same for the field
linked to biblioitems.url.
The url should not be sanitized, it may contain "&amp;".
3/ Launch the maintenance script with the -h parameter to see how to use
it.
4/ Launch the script using the different parameters:
 --filename=FILENAME
 --biblionumbers='XXX'
 --auto-search

The auto-search permits to sanitize all records containing "&amp;amp;" in
the marcxml field.

Use the verbose flag for testing.
Without the --confirm flag, nothing is done.

5/ Use the --confirm flag and verify in the biblioitems.marcxml field
that the record has been sanitized.

6/ Try the --reindex flag to reindex records which have been modified.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Bug 8218: Follow-up for some small typos

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Bug 8218: qa followup

This patch
- rename _entity_clean as _clean_ampersand
- rename the script to sanitize_records.pl
- add a --fix-ampersand switch (the only one FOR NOW, enabled by
  default) so it is obvious what the script does.
- make POD and usage reflect this changes.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>