1. remove the feature redundant name in all feature controllers(e.g.
'federatedlearningJob' to 'job'), since it has already own independent
package, no need the feature extra name
2. upstream interface optimizaztion
3. fix empty Kind of all CR in downstream
4. add extra doc string
5. fix code style

Signed-off-by: llhuii <liulinghui@huawei.com>

Since all CR watch actions are placed into corresponding controller,
controllers/downstream.go is unnecessary.

Signed-off-by: llhuii <liulinghui@huawei.com>