Remove react-emotion from tutorial

[garrowp]

Emotion removed react-emotion package. Not sure which version to put this in but part 4 of the tutorial will be fixed.

[DSchau]

Unfortunately, it's not quite this simple. We'll need to make more substantive changes to the tutorial to account for the changes in emotion 10, or perhaps we take this time to tweak the tutorial to use styled-components.

See #10226 for some more detail there, or see the upgrade guide for the shift in thinking from class names to styles and using the css prop.

[KyleAMathews]

@DSchau we're discussing switching in styled components?

[DSchau]

@KyleAMathews sorry missed this, but yeah - there are some changes in emotion 10 that make things slightly more complicated--at least at first glance.

I need to dive in a bit more before I fully propose that though.

@LekoArts and I have also talked about it briefly. If the changes in emotion 10 seem substantive enough, styled-components could be a little more beginner friendly, and more applicable to beginners.

[KyleAMathews]

We should in the meantime add to the install instructions that people are installing v9 of emotion. https://twitter.com/radhigulati/status/1070086832048619520

[agneym]

The sheer number of plugins that are being installed in the tutorial could be a bit confusing for a beginner (@emotion/core emotion/styled emotion gatsby-plugin-emotion emotion-server and much more available in docs) Switching over the tutorial to styled-components should be nice and easy for the tutorial purpose.

[shannonbux]

So for now, @garrowp it sounds like it's best to stick with Emotion v9 and make that clear. Do you mind changing this PR to account for that change?

Then, the suggestions to either use emotion v10 or styled components ought to be put into another issue. @boywithsilverwings and/or @DSchau, want to make that issue?

[ChristopherBiscardi]

@DSchau I'm happy to handle the upgrading to emotion 10. The old APIs still work but if you use the new APIs you get config-less serverside rendering, etc. Also some of the packages are no longer required.

[DSchau]

Going to close this out.

The complexity argument is certainly noted here, but I think that's a separate discussion. Happy to have it, just don't think it's applicable here.

As we've made some changes to the tutorial to account for Emotion 10, we can safely close this out.

See #10307 and #10306 for further context.