HPCC-8920 Implement challenge/response authentication in DALI & ESP

When ESP sends a file permission request to DALI it currently includes the username and password. These credential could be captured by an eavesdropper and used to gain access.
This change implements a mutual challenge/response handshake where both DALI and ESP are challenged by each other, and if successful, the file permission request is performed. Successful C/R exchanges are cached for a configurable period of time since it is likely more than one request will come from a given user
New configuration parameters (DALI and ESP)include a flag to indicate whether C/R should be enabled, an encrypted secret large digit that will be used as part of the hash, and a cache timeout. (see HPCC-9886)

Signed-off-by: William Whitehead william.whitehead@lexisnexis.com