HPCC-9216 DALI should cache rarely modified def file perms setting

Currently, DALI calls out to LDAP to get the default file permission
with every single scope verify call. This could be 100,000 or more
calls if iterating all files in production. Better solution is to
cache this value and only query it periodically

Signed-off-by: William Whitehead <william.whitehead@lexisnexis.com>