Add support for SQL across multiple tables to the explorer

[alvrs]

For example, this query works via the API, but not via the explorer SQL input:

curl -X POST https://indexer.mud.redstonechain.com/q \
-H "Content-Type: application/json" \
-d '[{
  "address": "0xf75b1b7bdb6932e487c4aa8d210f4a682abeacf0",
  "query": "SELECT Position.entityId, Position.x, Position.y, Position.z FROM Position, ObjectType WHERE Position.entityId = ObjectType.entityId AND ObjectType.objectTypeId = 84 AND Position.x >= 276 AND Position.x < 308 AND Position.y >= 3 AND Position.y < 35 AND Position.z >= 33 AND Position.z < 65"
}]'