The workflow terminate and purge APIs currently take a `non_recursive`
parameter to indicate whether to delete the workflow and its children.
This is a double negative and is confusing for users, needing a few more
brain cycles to understand the field. We should avoid double negatives
in APIs. This PR changes the parameter to `recursive` to make it more
clear.

`recursive` defaults to `true`.

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>