feat: Implement efficient node lookup table using node indices (#463)

Major Changes:
- Add generic Lookup<T> structure for efficient O(1) module-level data access
- Combine separate scope and order lookups into unified QuerySchedule structure
- Add query_schedule field to Interpreter for dedicated user query scheduling
- Refactor loop hoising to separate module
- Use efficient lookup for loop vars
- Also added more tests for loops

Key Concept:
- Ensure module context and indexing stay synchronized during function calls

Testing:
- All scheduler and interpreter tests passing

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/lib.rs

@@ -30,6 +30,7 @@ mod engine;
 mod indexchecker;
 mod interpreter;
 mod lexer;
+mod lookup;
 mod number;
 mod parser;
 mod policy_info;