Bug 8558: Improve confirmation message for importing frameworks

Bug 8558: Improve confirmation message for importing frameworks

This patch updates the confirmation message from:
"Do you really want to import the framework fields and subfields? This
will overwrite the current configuration. For safety reasons please use
the export option to make a backup"
to:
"Are you sure you want to import the [% frameworkcode %]
framework structure? This will overwrite the current configuration. For
safety reasons, it is recommended to use the export option to make a
backup first."

To test:
1) Go to Administration -> MARC bibliographic frameworks
2) Export one of the frameworks
3) Create a new test framework
4) Import the new test framework structure using the exported file
5) Upon clicking Confirm, confirm the message is improved and makes
sense.

Sponsored-by: Catalyst IT
Signed-off-by: Liz Rea <wizzyrea@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit e4d1318550af78f76b7a43757bbdc4c5bddb4d5f)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>