Allow configs to be set with string values

[andygrove]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
In Ballista, I have key-value pairs for configs that I would like to pass along to DataFusion. However, ifI set configs this way and then DataFusion calls get_u64 or get_bool, it will ignore the config because it has the wrong type.

Describe the solution you'd like
I would like to be able to pass string for any config and have DataFusion convert to the correct type.

Describe alternatives you've considered
None

Additional context
None

[comphead]

Hi @andygrove, reg to your config comment #3522 (comment)

We refused to introduce automatic cast in get_bool, get_u64.
I would like to be able to pass string for any config and have DataFusion convert to the correct type. -> this sounds like automatic cast still needed?