Standard library functions for `ion jq`, to interact with or create Ion types

[jobarr-amzn]

Several of the Ion types can be sensibly interacted with using jq, but sometimes we have e.g. a timestamp and we want to perform some operation on it. Or we want to create one. Or perhaps we want to create an sexp... can this be done?

[jobarr-amzn]

It is likely possible for us to add our own Ion-type-handling std library functions to our implementation of jq, since our jq capability comes from jaq which has extension points for adding your own functions (see jaq/jaq-std/src/lib.rs).