feat(blog): add sorting, better rendering

[leohhhn]

Description

This PR adds two new AVL trees that enable sorting of the blog posts by publication date and title.
This approach utilizes the fact that the AVL tree iteration order is lexicographic by key. We introduce two new AVL trees into the Blog struct - which store a key to sort by (title or publication date), and store the pointers to posts, meaning the memory overhead is small.

This PR also modifies the rendering of the blog:

Old blog home page:

New blog home page (sorted newest-top-left):

Old post rendering - header & footer:

New post rendering - header & footer:

The API changes are the following:

• Each post now stores the publisher (ie caller of ModAddPost), and the authors.
• It is envisioned that the author list will be a list of GitHub usernames, while the publisher is simply the address of the caller. A PR in the Blog repo will be added to accommodate this change.
• If the author list in the frontmatter of the blog post is empty, just the publisher will be displayed
• The timestamp for when the blog was written will primarily be taken in from the outside world, ie from the frontmatter, in the RFC3339 format. This timestamp allows us to still keep the ordering of the blogs even when the block height/timestamp is unreliable. In case the timestamps are not provided, time.Now() in the realm will be used instead.

Publishing flow - two options:

• Pass in data directly to the blog realm via ModAddPost,
• Use the gnoblog-cli or similar parsing & publishing tool.
  Either way, it is expected that any timestamps passed will be used in the time.RFC3339 format.

This PR is being published in pair with a refactor of the gnoblog-cli tool.

Related: gnolang/blog#20

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 47.48%. Comparing base (16c7c2e) to head (60a5d61).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1541      +/-   ##
==========================================
+ Coverage   47.41%   47.48%   +0.06%     
==========================================
  Files         385      385              
  Lines       61319    61408      +89     
==========================================
+ Hits        29074    29159      +85     
+ Misses      29826    29812      -14     
- Partials     2419     2437      +18     

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[leohhhn]

There is currently a bug in the rendering of the realm, specifically related to parsing time.Time. Putting this PR on hold until we figure out what is going on - it seems that it is a deeper issue than just the blog code.

Bug in question: #1588

The issue mainly happens when there is no date provided in the frontmatter of the blog post README, which is somethign that shouldn't really happen in our case, since there is a review process in place.

[leohhhn]

Currently cannot figure out why CI is failing - both examples lint & examples test fail because of the same reason:
gno test . --verbose at r/gnoland/pages displays a panic from the VM, even if the pages_test.gno file contains no tests. r/gnoland/blog tests pass fine.
Panic in question

Other than that, PR can be reviewed. It is supposed to be used in sync with the refactor of the gnoblog-cli.
This is the first in a series of PRs I have for making the blog better.

Edit: fixed in 4283930

[thehowl]

Suggest reverting the changes to Comment and then we should be good to merge