lib-sieve: program-client was moved to dovecot core

src/lib-sieve/util/Makefile.am

src/lib-sieve/util/program-client-local.c

src/lib-sieve/util/program-client-private.h

src/lib-sieve/util/program-client-remote.c

src/lib-sieve/util/program-client.c

src/lib-sieve/util/program-client.h