lib-sieve: sieve-storage - Use int for sieve_storage_open_script() status result

src/lib-sieve/sieve-script.c

src/lib-sieve/sieve-storage.c

src/lib-sieve/sieve-storage.h

src/managesieve/cmd-deletescript.c

src/managesieve/cmd-getscript.c

src/managesieve/cmd-renamescript.c

src/managesieve/cmd-setactive.c

src/plugins/doveadm-sieve/doveadm-sieve-cmd-activate.c

src/plugins/doveadm-sieve/doveadm-sieve-cmd-delete.c

src/plugins/doveadm-sieve/doveadm-sieve-cmd-get.c

src/plugins/doveadm-sieve/doveadm-sieve-cmd-put.c

src/plugins/doveadm-sieve/doveadm-sieve-cmd-rename.c

src/plugins/doveadm-sieve/doveadm-sieve-sync.c

src/plugins/imap-filter-sieve/imap-filter-sieve.c

src/plugins/imapsieve/imap-sieve.c