CVE-2024-8932: fix out-of-bounds write in ldap_escape() by bounding the
escaped-length accumulation in php_ldap_do_escape() against ZSTR_MAX_LEN
and raising a ValueError instead of overflowing size_t in ext/ldap/ldap.c
(GHSA-g665-fm4p-vhff); add regression tests
ext/ldap/tests/GHSA-g665-fm4p-vhff-1.phpt and
ext/ldap/tests/GHSA-g665-fm4p-vhff-2.phpt