Fixing cdd_gae gen parquet -> sqalalchemy table

[skushnir123]

Fixes two bugs which caused this command: python -m cdd_gae gen --parse 'parquet' --emit 'sqlalchemy_table' -i "$parquet_file" -o "$py_file" --name "$table_name" to fail.

• ast_utils updated to handle Assigns, not just classes and functions. This is critical for Sqlalchemy tables as they are inherently Assign expressions.
• updated infer imports. A map was expecting a 1d array but was receiving a 2d array so chain(2d array) fixed it.