Only calculate dependent functions / inputs in a field transform / treeElement transform data preview on function level

When re-using Field Transforms you often need to update functions however the preview of a single function will not work until every transform function is correctly updated otherwise it throws an error for a function you intended to fix later. The suggestion is to make a function preview independent of other functions not used in that individual function so you can then properly fix one at a time without needed them all to work simultaneously.