* modifying simdjson::from to avoid exceptions when needed.
* moved the function
* moving the strings.
* more moving around
* updating cmake version in ci
* This is a small reorg of the new convert code so that we only expose 'simdjson::from'.
This can be changed in a future release, but we don't want our users to start depending
on code that we might need to change.
* marking simdjson::from as experimental
* updating tests to match recent changes