* Allow custom transformations of assets
This exposes one query parameter `transforms`, which is a JSON array of
shard transformation operations.
It also updates the asset presets. The UX for this still needs some work
* Rename options to arguments for presets
More explicit
* options -> arguments in setting spec
* Better errors for invalid JSON in asset presets
* Add limit to transforms query parameter
* Use flattened option for extra transforms
* Fix placeholder color of code input
* Allow "simple mode" aliases
* Add documentation
Co-authored-by: rijkvanzanten <rijkvanzanten@me.com>
