feat: Add CONTAINS and NOT CONTAINS operators for substring matching

[ArchishmanSengupta]

What was changed

Add support for CONTAINS and NOT CONTAINS operators to enable substring matching in SQL queries.

Changes:

• token.go: Register contains as a reserved keyword
• ast.go: Add ContainsStr and NotContainsStr operator constants
• sql.y: Add CONTAINS to operator precedence and grammar rules
• sql.go: Regenerate parser from updated grammar using goyacc

Example usage:

SELECT * FROM workflows WHERE WorkflowId CONTAINS 'azure-ad'
SELECT * FROM workflows WHERE WorkflowType NOT CONTAINS 'test'

Why?

Currently, the parser only supports prefix matching via STARTS_WITH. This limitation makes it difficult to perform substring searches within field values, which is a common filtering use case.

Use case: Users need to find all workflows containing a specific substring in their WorkflowId or WorkflowType. For example:

• Finding workflows: atom-agent-azure-ad-1, service-azure-ad-sync, azure-ad-integration-v2 by searching for substring "azure-ad"
• This is not possible with STARTS_WITH alone since the substring may appear anywhere in the value

The CONTAINS operator complements STARTS_WITH by enabling substring matching at any position, providing more flexible filtering capabilities.

Related Changes

This PR is part of a feature implementation across multiple repositories:

1. sqlparser (this PR): Add CONTAINS operator to SQL grammar
2. Temporal Server (PR Link): Use CONTAINS in visibility query converters
   • Convert CONTAINS → SQL LIKE '%value%' for SQL databases
   • Convert CONTAINS → Elasticsearch WildcardQuery("*value*")
3. Temporal UI (PR Link): Add "Contains" filter option in workflow search UI

All three PRs need to be merged together for the feature to work end-to-end.

Checklist

1. Closes #[issue number if exists]

2. How was this tested:

   • ✅ Parser correctly tokenizes CONTAINS keyword
   • ✅ AST properly represents CONTAINS and NOT CONTAINS expressions
   • ✅ Operator precedence works as expected
   • ✅ Grammar rules parse both CONTAINS and NOT CONTAINS variants
   • ✅ Tested with Temporal Server integration - queries execute successfully
   • ✅ Manual testing: WorkflowId CONTAINS "azure-ad" returns correct results

3. Any docs updates needed?

   • No documentation exists for this library currently
   • Usage will be documented in Temporal Server docs as part of visibility query syntax

Implementation Notes

• Added as a separate precedence line and at the end of grammar rules for minimal diff
• Follows the same pattern as STARTS_WITH operator
• Only 13 lines added to source files (token.go, ast.go, sql.y)
• The large diff in sql.go is auto-generated by goyacc and is expected