Add a way to check the sources

[july2993]

Feature Request

Is your feature request related to a problem? Please describe:

After adding some sources. ref https://pingcap.com/docs-cn/tidb-data-migration/dev/manage-source/#%E5%8A%A0%E8%BD%BD%E6%95%B0%E6%8D%AE%E6%BA%90%E9%85%8D%E7%BD%AE

root@control:/tiup-cluster# dmctl --master-addr n1:8261 operate-source create ./_dev/dm/source1.toml
{
    "result": true,
    "msg": "",
    "sources": [
        {
            "result": true,
            "msg": "",
            "source": "mysql1",
            "worker": "dm-172.19.0.104-8262"
        }
    ]
}

there's no way to check the sources?
how can I know what sources I have later? And check some issues like if some sources have no worker?

Describe the feature you'd like:

Add a way to check the sources

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

[lance6716]

going to add show-source (or operate-source show, which is better?), to list added sources and its bounding worker.

BTW, similar to #398, we should re-orgnazation commands someday 😂, for example, support CRUD as second argument for source/task/...

@csuzhangxc PTAL at your convenience

[csuzhangxc]

@lance6716 I think operate-source show is better.

BTW, similar to #398, we should re-orgnazation commands someday 😂, for example, support CRUD as second argument for source/task/...

You are right! 😂