Bug 34098: Improve translation of some strings in the patron import template

Bug 34098: Improve translation of some strings in the patron import template

This patch updates a few sections of the patron import template in order
to import the way strings are identified for translation.

To test, apply the patch and install another translation if necessary.

- Go to Tools -> Import patrons
- Under "Notes," you should see a link, "Download a Starter CSV file
  with all the columns."
- Test the process of importing a batch of patron records.
  - When the import completes, confirm that the status messages are
    correct:

    X imported records
    X overwritten records
    X not imported because they are already in borrowers table and
      overwrite is disabled
    X not imported because they are not in the expected format
    X records parsed

TESTING TRANSLATABILITY

- Update a translation, e.g. fr-FR:

> cd misc/translator
> perl translate update fr-FR

- Open the corresponding .po file for the updated strings, e.g.
  misc/translator/po/fr-FR-messages.po
- Locate strings pulled import_borrowers.tt for translation and confirm
  that they are readable and have context information under 'msgctxt'

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>