labs: turn `rrrepl` into a timeline client

[bnjbvr]

It's called multiverse because it allows you to explore multiple timelines.

The rrrepl client is now a small TUI app, that can either show the state of read receipts for all the rooms, or render all the timeline items that are messages. There are likely a few bugs in and there, but it's already quite sufficient to analyze some behaviors and reproduce real-world problems.

Screencast from 2024-02-27 15-02-28.webm

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 22 lines in your changes are missing coverage. Please review.

Project coverage is 83.78%. Comparing base (cb6b420) to head (4ad79d6).

Files	Patch %	Lines
labs/multiverse/src/main.rs	0.00%	22 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3178      +/-   ##
==========================================
- Coverage   83.85%   83.78%   -0.08%     
==========================================
  Files         232      233       +1     
  Lines       24004    24026      +22     
==========================================
  Hits        20129    20129              
- Misses       3875     3897      +22     

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