Add git-history extractor / plotter

[yarikoptic]

Motivation is - to be able to produce historical plots when necessary. Quick and dirty script which seems to work -- https://github.com/con/git-annex-log-stats/blob/ef51e84377002645fe5c5b94da75c2d1e4e55d10/git-annex-log-stats.py .

Sample plot and more info/pointers:

-- with LLM (Claude did quite good!) wrote a couple of scripts and ran
across what I have already "published" on datasets.datalad.org -- so it
is not complete set unfortunately so the plot might not be representative and should not be used as is, but I
will see to get it more exhaustive and uptodate with time. But here you
go

https://github.com/datalad/datasets.datalad.org-gitlog-stats/blob/master/plots/neurorepos-1.svg

and if you have a bunch of git/git-annex repos should be quite easy to
establish similar dedicated plots - those crude scripts are at

https://github.com/con/git-annex-log-stats

with sample output of stats collected across all git repos on
datasets.datalad.org under stats/ folder of that

https://github.com/datalad/datasets.datalad.org-gitlog-stats/tree/master/stats

and the overall plotting invocation at

https://github.com/datalad/datasets.datalad.org-gitlog-stats/blob/master/code/plot_all.sh

Notes:

• not sure yet if we want right away to exract/consolidate historical data into DB or just keep those json records as yet another metadata.
• it would require full clone (can no longer be depth 1 if that is what we do)