BibIndex: new 'all-virtual' CLI option

• Introduces new '--all-virtual' option which is an equivalent of '-w virtual_ind1,virtual_ind2,etc.

• Running bibindex without parameters won't run update for virtual indexes.

Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>