feat: Add SQL Query Summary - Tokenizer, Parser, Cache

[hannahramadan]

This PR adds the framework for a query summary generator, including a tokenizer, parser, and cache. It is meant to generate the db.query.summary attribute for database spans.

Query Pipeline: SQL Query → Cache Lookup → Tokenizer → FSM Parser → Summary

Fast Path & Caching

• Tiered Processing: High-frequency CRUD queries (e.g., SELECT * FROM table) use pre-compiled regex to bypass tokenization.
• LRU Cache: Thread-safe caching (default size: 1000) prevents redundant processing of identical SQL fingerprints.

Tokenizer

• Breaks SQL into typed tokens (:keyword, :identifier, :operator) using StringScanner.
• Filters sensitive data like string literals, comments, numeric values
• Optimization: Uses a hash-based keyword lookup and frequency-ordered scanning to minimize

Parser

• 3 States: PARSING_STATE (verb hunting), EXPECT_COLLECTION_STATE (table gathering), and DDL_BODY_STATE (skipping procedure/trigger internal logic).
• Manages implicit aliases, JOIN lists, UNION consolidation, and IF EXISTS DDL patterns.

Summary Generation

• Consolidates operations and table names: "SELECT users profiles".
• Truncates at 255 characters
• Automatically removes duplicate table names in complex joins or unions

Resources:

• Spec: Generating a query summary
• .NET implementation and test cases

[hannahramadan]

db.query.summary should be used as a database span name, but if the summary is not available, then the name should be {db.operation.name} {target}. We should keep that in mind when changing db instrumentation. If the return value of the summary is UNKNOWN, then we have more work to do to create the span name.