Add missing SessionContext utility methods

[timsaucer]

Summary

Several utility and introspection methods on SessionContext from upstream DataFusion v53 are not yet exposed in datafusion-python.

Missing Methods

• parse_sql_expr — parse a SQL expression string into a logical expression
• execute_logical_plan — execute a logical plan and return a DataFrame
• refresh_catalogs — refresh catalog metadata
• session_start_time — get the session start time
• enable_ident_normalization — configure whether identifiers are normalized (lowercased)
• add_optimizer_rule — add a custom optimizer rule
• remove_optimizer_rule — remove an optimizer rule by name
• add_analyzer_rule — add a custom analyzer rule
• table_provider — get a TableProvider by name

Upstream Reference

• https://docs.rs/datafusion/53.0.0/datafusion/execution/context/struct.SessionContext.html

Implementation

• Rust bindings: crates/core/src/context.rs
• Python wrappers: python/datafusion/context.py

Notes

Some of these (optimizer/analyzer rules) may require exposing additional Rust types to Python, which could be complex. parse_sql_expr and execute_logical_plan are likely the most immediately useful.

Note: This gap analysis was performed using an AI agent comparing upstream DataFusion v53 documentation against the current datafusion-python codebase.