Add support to create yamls of existing entities

[ejseqera]

Based on some conversations internally, it seems it would be useful to have a seqerakit dump feature where a YAML is generated for all entities in a given workspace, allowing people to see changes between YAMLs that are initially defined to create entities versus what exists.

Right now, we can only export and import pipelines and compute envs to define entities via CLI, everything else would require parsing some output of tw <subcommand> list? Not sure if this would work so we would have to test this a couple times with resources such as participants, datasets, etc.