Bug 24616: Allow copying notice to a branch even if it exists in that branch

Bug 24616: Allow copying notice to a branch even if it exists in that branch

If you try to copy notice or slip to a branch which already
has that notice or slip Koha won't let you save it. Instead
pop-up saying branch already has that notice is displayed.

This patch allows users to copy and override already existing
notice or slip.

To test:
1. Find notice which exists e.g. in all branches and branch A.
2. Copy that notice, add notice screen is displayed.
3. Press save.
=> Pop-up informing that notice already exists in branch A
is displayed.
4. Apply this patch.
5. Repeat steps 2. and 3.
6. Pop-up to confirm overwrite of notice is displayed.
=> Confirm that if you press OK, notice is saved succesfully.
=> Otherwise, changes to notice should not be saved.

Also try to save the notice you tested with as a new (same code)
to branch A. Confirm that pop-up is displayed as it should be.

Sponsored-by: Koha-Suomi Oy
Signed-off-by: Nick <nick@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>