Setup Javascript resources to use released artifacts by default

[mbauman]

There are three parts to this pull request, and this can easily be split apart if that's preferred.

• f9ffcb0: Creates a GitHub Action that allows you to create releases of the two javascript dependencies directly on JuliaPlots/PlotlyKaleido.jl. It's a manually triggered action that allows you to set the desired version number. It downloads the given javascript resource for the given version, uploads it as a release artifact, and then creates pull request(s) to update the Artifacts.toml as needed.
  

• f41323d & a308b5d: Are the results of merging Update plotly artifact to v2.35.2+2 mbauman/PlotlyKaleido.jl#4 and Update mathjax artifact to v2.7.9+0 mbauman/PlotlyKaleido.jl#5 on my fork.

• 5b462a0: is a minimally invasive patch to default to using these artifacts from my fork.

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There are two paths forward here, and I'm happy to help make either happen:

• merge this PR as is, and then an owner here triggers the plotly and mathjax release builds (and subsequent PRs) to move update the Artifact.toml to use those official releases.
• I can split this to just contain f9ffcb0, then an owner here can trigger the actions, then merge the auto-generated PRs, then I can submit f41323d.

Fixes #26.

[BeastyBlacksmith]

Thank you for investing the time to set this up. I would be fine to merge it as is and trigger the action.

Should we keep using the artifacts already present on your fork or use the then generated ones here?

[mbauman]

Personally, I think it looks much more professional to use releases on the proper repo in the proper org. I think it's worth doing. The reason I got up to a 2.35.2 +2 on my plotly release version was just to test out the +buildsuffix support. I'm also liable to accidentally delete a fork after forgetting that we're doing this.

[BeastyBlacksmith]

Personally, I think it looks much more professional to use releases on the proper repo in the proper org.

We do that then

[BeastyBlacksmith]

One thing I noticed is, that if you trigger both artifact builds the pull-requests will overwrite each other instead of either opening two PRs or create a PR with both updates (#28)