feat(search): add a flag to dump DOT graphs in FT.EXPLAINSQL

[PragmaTwice]

$ redis-cli -p 6666 --raw
127.0.0.1:6666> ft.explainsql 'select * from testidx where a hastag "z" and b < 30' dot
digraph {
  x7fdb3c003940 [ label = "Projection" ];
  x7fdb3c003940 -> x7fdb3c003bf0;
  x7fdb3c003bf0 [ label = "Filter" ];
  x7fdb3c003bf0 -> x7fdb3c003a30;
  x7fdb3c003a30 [ label = "TagFieldScan (z)" ];
  x7fdb3c003a30 -> x7fdb3c003580;
  x7fdb3c003580 [ label = "FieldRef (a)" ];
  x7fdb3c003bf0 -> x7fdb3c003ba0;
  x7fdb3c003ba0 [ label = "NumericCompareExpr (<)" ];
  x7fdb3c003ba0 -> x7fdb3c003aa0;
  x7fdb3c003aa0 [ label = "FieldRef (b)" ];
  x7fdb3c003ba0 -> x7fdb3c003b50;
  x7fdb3c003b50 [ label = "NumericLiteral (30)" ];
  x7fdb3c003940 -> x7fdb3c001b10;
  x7fdb3c001b10 [ label = "SelectClause" ];
}

[sonarcloud]

Quality Gate passed

Issues
12 New issues
0 Accepted issues

Measures
0 Security Hotspots
61.6% Coverage on New Code
1.8% Duplication on New Code

See analysis details on SonarCloud