HPCC-12012 Cache PackageMaps/PackageSets info in WsPackageProcess

The PackageMaps/PackageSets info is cached into WsPackageProcess
in order to avoid unecessary calls to dali. Subscribe/notify is
used for dali to notify the ESP service about possible changes
of the PackageMaps/PackageSets info.

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>
HPCC-12012 Revise based on code review

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>
HPCC-12012 Revise exception wording

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>
Merge pull request #6306 from wangkx/cache_package_map

HPCC-12012 Cache PackageMaps/PackageSets info in WsPackageProcess

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>