Index string ownership

[jeffreylovitz]

Fix assertion error and invalid memory accesses described at RedisGraph/redisgraph-py#57

[swilly22]

We need to add an AST validation

match (a) where a.v in 3 return a

Neo.ClientError.Statement.SyntaxError: Type mismatch: expected List<T> but was Integer (line 1, column 32 (offset: 31))
"explain match (a) where a.v in 3 return a"

GRAPH.EXPLAIN g "match (a) where a.v in 3 return a"
1) "Results"
2) "    Project"
3) "        Filter"
4) "            All Node Scan | (a)"