Security: Needed schema fix-ups

[Jaymassena]

• [x] users: add created_by
• [x] channels (group-channels): add owned_by (for primary owner)
• [x] channels (group-channels): rename group to group_id
• [x] messages (group-messages): rename group to group_id
• [x] messages (group-messages): rename channel to channel_id
• [x] group-members: add created_by and created_at
• [x] group-channel-members: add created_by and created_at
• [x] group-channel-members: symmetrical with member-channels
• [x] member-groups: add created_by and created_at
• [x] member-channels: add created_by and created_at
• [x] member-channels: copy to group-channel-members

Need fix-up: Copy key (userId) to created_by and copy joined_at to created_at

[Jaymassena]

Done