Remove unused xeus-cling and xtensor images

[mcbarton]

As far as I can tell these images are not being used anywhere in the repo, so this PR removes them.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.05%. Comparing base (5860e95) to head (da0796e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #404   +/-   ##
=======================================
  Coverage   82.05%   82.05%           
=======================================
  Files          21       21           
  Lines         858      858           
  Branches       89       89           
=======================================
  Hits          704      704           
  Misses        154      154           

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[anutosh491]

Well xtensor stack (xtensor, xsimd, xtensor-blas etc) is like only set of repos for which we support fetching online documentation right now as can be seen from our link on the xeus-cpp-wasm repo.

So not mentioned anywhere but yeah probably that's the reason we had the xtensor image :\

[vgvassilev]

Yes, but why is this different than other libraries?

[anutosh491]

Yes, but why is this different than other libraries?

I think that's because xeus-cling which was maintaining the responsible tagfiles for separate libraries as shown here (https://github.com/jupyter-xeus/xeus-cling/tree/main/etc/xeus-cling/tags.d). This is the not best approach right ? we don't want to host tagfiles for each library in our code.

Rather how xeus-cpp does it is, if a library author wants to support inline documentation through a notebook, they just need to generate and host tagfiles in their source itself and when we fetch the package the tagfiles land in our prefix from where we can use them.

I think Johan and I discussed this long back but yeah this can be improved on I think for sure ? Some kind of mechanism to generate the required files basically !