SNOW-884382: Add support for setting row_access_policy

[rymndhng]

What is the current behavior?

The SnowDialect DDL does not support defining a row access policy.

What is the desired behavior?

To be able to define a row access policy using sqlalchemy.Table, like so:

sqlalchemy.Table(
   ...,
   snowflake_row_access_policy=('my_policy_name', ["field_1", "field_2", "field_3"])
)

How would this improve snowflake-connector-python?

References, Other Background

This is similar to specifying snowflake_clusterby.

[sfc-gh-dszmolka]

hi and thank you for raising this issue with us, we'll consider this requirement for the future plans. if there's any chance of submitting a PR, that would be greatly appreciated.