Bug 26459: Add hold-mode option to sip_cli_emulator

Bug 26459: Add hold-mode option to sip_cli_emulator

To test:
1 - Apply patch
2 - Restart all
3 - Place an item level hold for a patron via the staff client
4 - Cancel the hold using the sip_cli_emulator with hold-mode: -
perl misc/sip_cli_emulator.pl -a localhost -p 6001 -su term1 -sp term1 --patron {cardnumber} --item {BARCODE}  -m hold -l CPL --hold-mode -
5 - Run the sip_cli_emulator with no params
6 - Verify help text is understandable

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>