ABAC policy functions now use snake_case naming

ABAC policy tag functions now use snake\ case naming (has tag, has tag value, has column tag, has column tag value), consistent with other Databricks SQL built in functions. The camelCase forms (hasTag, hasTagValue, hasColumnTag, hasColumnTagValue) continue to work for backward compatibility, but Databricks plans to deprecate their use when creating new policies in the future. Databricks recommends updating any new policies to use the snake\ case forms.