Feature Request: Change the permission of a note

There is no easy way to change note's permission in mass. While I can mass import Markdown note with this CLI, I cannot seem to control the permission of those notes with CLI. And it is a painstakingly long process to do it one-by-one on the web GUI.

It would be great if there is a command like this:
```
hackmd-cli chmod [NOTEID] [[-r|--readable] [owner|login|everyone]] [[-w|--writable] [owner|login|everyone]]
```

Example,
```
$ hackmd-cli chmod some-note-id -r everyone -w login
Permission of your note https://hackmd.io/some-note-id has changed.
Readable: everyone
Writable: login
```

Start by reviewing the existing CLI path for mass Markdown note import and how note identifiers are handled. Then determine how the proposed chmod arguments map to HackMD permissions and verify the command's success output and readable/writable settings for owner, login, and everyone.

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