Lookup in Transforms

Requirements

1. Operations
   1. Perform single + batch read on single + multiple dataset from script transform
   2. Perform single + batch read on DistributedCache from script transform
2. Supported datasets for lookup
   1. Key-value table
   2. ObjectMappedTable
3. Optional caching with time-based expiration

Design

1. LookupKV interface
   1. Object lookup(String key);
   2. Map<String, Object> multiLookup(String[] key);
2. ScriptTransform
   1. Add configuration property for declaring lookup tables to use, properties for each table (e.g. dataset properties)
   2. configure(): verify datasets / tables exist
   3. transform(): execute lookup methods in a transaction