Use public property names for Format properties

[agavra]

See: #4437 (comment)

We want to be able to have pluggable schemas in the future, and formats often need configurations (e.g. VALUE_DELIMITER for the DELIMITED format) that are passed in the WITH clause. Today, there is a mapping from the public config name to what is used internally (e.g. VALUE_DELIMITER -> "delimiter"). When we support pluggable schemas, this mapping should be removed and we should just use the public name.

This may mean we need to change the way we pass the format specification in the WITH clause. For example, we could do something like:

WITH(value_format=FORMAT(name='DELIMITED', value_delimiter=','), key_format='KAFKA')