cmd/inspect: Update inspect to pretty print by default (#4021)

Inspect previously pretty printed only when -f pretty was specified. This change ensures that inspect pretty prints by default, and a user can specify --format=json to avoid relying on implicit default behaviour.

Fixes: #4021

Signed-off-by: Emily Tao
<tao.emily@yahoo.ca>
Signed-off-by: Emily Tao <tao.emily@yahoo.ca>