Publish workflow

[LFDanLu]

Notable changes from jenkins:

• build and deploy is triggered by pushes made to next branch, no more pressing a button with a drop down selection for patch version
  • As a consequence, the Makefile's lerna version step needs to be manually changed to what kind of release we want to do for now. For now I've set it to lerna version 3.0.0for our first upcoming release. If we adopt conventional commits, I can remove this.

Changes in this pull:

• all available packages that are slated to go out for our first release have their private: true removed and source/main/files fields in their package.json modified. Root level index.ts has been added so typescript module resolution doesn't trip up from the prior mentioned changes
  • something to note is that some of the Milestone 1 components (e.g. datepicker) have dependencies on components that aren't in Milestone 1 (e.g. calendar)
• spectrum css package has post css run on it before package publish
  • postcss config stuff has been moved around as a consequence.
• Makefile build/version/publish changes
• update to plop stuff so new v3 packages have the same main/source etc configured

TODOs not included in this pull (unless we want these in here as well?):

• conventional commits so we can do lerna versioning automatically
• creds for npm publishing and the actual npm registry to which we will publish our packages need to be added
• exhaustive testing of the packages themselves. I did some testing with a react-create-app but it would be good to do some more
• merge the rest of the v3 components that exist in the old repo and apply the same changes I made in here to those components. This includes removing private: true, main/source changes, and adding a package root level index.ts
• add website/doc deploy steps once we actually have a place to put them

[github-actions]

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[github-actions]

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[dannify]

Replaced by #17