Get WAREHOUSE_YML_FILE default value from an environment variable

[stumelius]

soda scan commands are quite verbose with the two positional arguments (WAREHOUSE_YML_FILE and SCAN_YML_FILE). You could change the WAREHOUSE_YML_FILE positional argument to a keyword argument (e.g., --warehouse-config) and use an environment variable (e.g,. SODA_WAREHOUSE_FILE) as the default value. This would be similar to what dbt has done with their profiles configuration.