Periodic check for updating reverse username mapping

[taoeffect]

Problem

I recall @corrideat saying that there's potentially an issue with the namespace reverse mapping where it's possible for non-human-readable contractIDs to be displayed in place of the username.

Solution

I think @corrideat said there might need to be some periodic, e.g. every 30 min or so, check for this.

[taoeffect]

Note: yesterday I joined a group @dotmacro had created on testing, and on her end I appeared as a z998wdfu89w type contractID after joining. I also didn't appear for her in the #general chatroom for her (even though on my end I had joined), and she wasn't able to create a DM to me.

I'll need to create a separate issue out of this but wanted to comment here before I forget as it might be somewhat related to this issue (but is likely different).

I looked at her logs but couldn't find anything in them unfortunately... maybe the error happened to early and got removed from the logs.

[taoeffect]

Created the issue! It's now a sub-issue of this issue. Added details here and how to reproduce: #2570