Add support for SQLAlchemy as export format

[characat0]

Closes #398

Summary

In this PR I propose to add basic support for SQLAlchemy, we can discuss further details here.

My particular use case is focused on databricks sql connection, but I would be happy to receive feedback from people with other use cases

Description

Table names and comments are supported, as well as field comments. Table schema support is still limited to schema only, with support for fully qualified schemas (catalog.schema) on autogenerated migrations depending on sqlalchemy/alembic#1526.

Data Types

I've currently implemented support for the following primitive data types:

• string: String with maxLength
• text: String with maxLength
• varchar: VARCHAR with maxLength
• number, decimal, numeric: Numeric with precision and scale
• int, integer: Integer
• long, biting: BigInteger
• float: Float
• double: Double
• boolean: Boolean
• timestamp: TIMESTAMP
• timestamp_tz: TIMESTAMP with tz=True
• timestamp_ntz: TIMESTAMP_NTZ (only supported in databricks)
• date: Date
• bytes: LargeBinary with maxLength

I've also added support for arrays of these type of primitives.

• Tests pass
• ruff format
• README.md updated (if relevant)
•  CHANGELOG.md entry added

[jochenchrist]

Thanks for this PR. I think, this is a very valuable contribution.

Please add a test case for this exporter.

[characat0]

@jochenchrist thanks for the feedback, I've added some test cases inspired by the Pydantic export implementation

[jochenchrist]

can you please also update the README and the CHANGELOG?