minors:
* add optional 'extraImages' to ThickCharts
* refactor File content into generic getter interfaces
* refactor artifact.Config into an actual usable interface (by File content)
* refactor 'copy' cli command to use oras mappers
* refactor 'serve' cli command to server registry and/or fileserver
* represent all content as artifact.OCI interface and manipulate/add all content using oci layouts
* initial brew taps and macos universal binary
* change mediaType to string for better compatibility with other libraries
* ensure config is minimally viable for file/charts
* add transparent layer caching (filesystem) to artifact operations, clean up layer interface used by file/chart
* add store list and store copy commands
Signed-off-by: Josh Wolf <josh@joshwolf.dev>
