Remove Requires-based GLMakie video player functions

[IanButterworth]

Compared to the Images ecosystem, which has ImageIO & ImageView / ImageInTerminal etc. it's never made too much sense that the Makie-based video player lives in here, even if it is behind Requires.

I regret not doing this before v1.0.0 because I think this means we'd need to release v2.0.0 after only a few patch versions.

Before releasing this, this functionality needs to be moved to another package.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.71%. Comparing base (e5bb24f) to head (8297527).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #385      +/-   ##
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+ Coverage   79.04%   79.71%   +0.66%     
==========================================
  Files          10       10              
  Lines        1284     1282       -2     
==========================================
+ Hits         1015     1022       +7     
+ Misses        269      260       -9     

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[timholy]

Removing or refactoring makes sense simply from the standpoint of precompilation (though an extension module would fix that).

If you're thinking about 2.0, have you also considered further changes? Video data seems array-like, with one or two caveats:

• in some applications (e.g., accessing a movie file), for img[i, j, k], updating k is much more "expensive" than i or j
• in some applications (e.g., a live webcam feed), you can't control k independently

The first can be viewed as something that could be expressed with a trait and thus might not be a hard-break of an array abstraction; the second makes video less clearly array-like. Are there enough other applications that these concepts would be worth encapsulating more abstractly? I attempted to do this with ImageAxes's StreamingContainer, but I don't think it's been widely adopted. There may be a better platform available now?