Add ability to set ORDER / NOORDER sequence on columns with IDENTITY

[DanielTatarkin]

Please answer these questions before submitting your pull requests. Thanks!

1. What GitHub issue is this PR addressing? Make sure that there is an accompanying issue to your PR.

   Fixes #436

2. Fill out the following pre-review checklist:

   • [x] I am adding a new automated test(s) to verify correctness of my new code
   • [ ] I am adding new logging messages
   • [ ] I am adding new credentials
   • [ ] I am adding a new dependency

3. Please describe how your code solves the related issue.

   CREATE TABLE DDL supports optional ORDER | NOORDER value for AUTOINCREMENT | IDENTITY sequences on a column. Before this change, using a column with a sequence like Column(NUMBER, Identity(start=1, increment=1, order=True) would default to session parameter NOORDER_SEQUENCE_AS_DEFAULT TRUE by default which would always set NOORDER instead of what is being set in the column definition.

   For us, this lead to discrepancies between ORM defined models and the Snowflake state seen by Alembic.

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[DanielTatarkin]

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[DanielTatarkin]

Semi-related issue #494

[DanielTatarkin]

Hi,

Thank you for your contribution 💪

Pls provide test cases proving correctness of proposed solution.

Example test case could look like this

def test_table_create_order():
    metadata= MetaData()
    table = Table("test_table", m, Column("pk", Integer, Identity(start=1, increment=1, order=True)))
    ddl_schema = schema.CreateTable(table)
    res = _schema.compile(dialect=SnowflakeDialect())
    expected = "..."
    assert res.string == expected, res.string

@sfc-gh-mraba thank you for the example, I added a unit test to tests/test_sequence.py (test_table_with_identity), let me know if the location is appropriate.