Introduce `ks component rm <component>`. This functionality will:

1. Delete the component file from components/. This is determined by the
component file name. If there exists two files with the same name but
different file  extensions, we will error out.

2. Remove component references. This currently implies removing all
component referenes in the component/params.libsonnet file and the
environment-specific params.libsonnet files.

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>