Enable supports_statement_cache for Db2 SQLAlchemy dialects

[bchoudhary6415]

This PR addresses issue #187 and enables SQLAlchemy statement cache support for the Db2 SQLAlchemy dialect (ibm_db_sa).
The change refactors LIMIT / OFFSET SQL compilation to ensure that:

• Compiled SQL strings are stable and reusable
• Bind parameters and post-compile parameters are preserved
• SQL text is not dependent on runtime values
• OFFSET-only queries are safely rewritten using ROW_NUMBER() while remaining cache-friendly
  As a result, the dialect can safely advertise:

supports_statement_cache = True

For more info related to it, please go through below documentation links of SQLAlchemy

• Dialect caching support: https://docs.sqlalchemy.org/en/20/core/internals.html#sqlalchemy.engine.Dialect.supports_statement_cache

• Caching requirements for third-party dialects: https://docs.sqlalchemy.org/en/20/core/connections.html#engine-thirdparty-caching