Allow export of a single channel/user/team

[svelle]

When using the mmctl export command it would be absolutely terrific to have the option of exporting only a selected user, channel or team instead of everything!

Something like

mmctl export --channel [channelid] mmctl export --team [teamid] mmctl export --user [username]

Cheers!

[isacikgoz]

Created the ticket: https://mattermost.atlassian.net/browse/MM-40522

[agnivade]

@svelle - Can you give some more context into this? Was this requested by a customer?

• Is the usecase to export a single channel from one server to another? Without exporting users, how would the posts look like? Do you expect ghost-like user profiles? Permalinks would be broken as well but that's less of a concern.
• What does exporting a single user mean? All posts for a user? But what if one reply was a child of a parent post? In a CRT world, how would that look? Would it even make sense to export posts without context of surrounding posts?