Bug 14853: Change 'Fund' to 'Shipping fund'

 Bug 14853: Change 'Fund' to 'Shipping fund'

Changes the 'Fund' to 'Shipping fund' so it's clear
what the fund setting is used for.

To test:
- Receive a new shipment
- Verify that 'Shipping fund' displays on the parcels page
- Search for your invoice
- View invoice details
- Verify that 'Shipping fund' displays on the invoice page

Followed test plan (changed lines: '...cost' -> '...fund')
Display OK on both places.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>