Runtime config options passed down to shims is awkward

### What is the problem you're trying to solve

#7764 added a field to pass a toml blob down to shims.
The type used to do this already has a field for typeurl and file path.
So we have two cases:

1. typeurl and confg path are set
2. toml blob is set

### Describe the solution you'd like

The implementation and docs should be updated to support passing down the actual type json described by the typeurl.
When typeurl is present shims could just use that to decode the blob from json, otherwise it can fallback to raw toml if needed (though it would be nice to not deal with toml at all).

### Additional context

_No response_