build: migrate to monorepo (for vue-jest@5)

[nogic1008]

⚠️ DO NOT merge this PR with "Squash & Merge" method!! ⚠️
It breaks package.json histories.

This PR is a part of #355.
Similar to #360, but targeted at next(vue-jest@5) branch.

Changes

• setup monorepo (use yarn workspace)
• move e2e/__projects__/* projects to e2e/3.x/*
• move package.json and lib/ to packages/vue3-jest/
• change package to vue3-jest@26.0.0-alpha.10
• fix e2e test for monorepo

[lmiller1990]

I left some comments.

I have a question that we did not think about. We will need to support multiple versions of Jest at the same time for a while - in this case, we need to maintain v26 and v27 support.

Should we have two packages? vue3-jest26 and vue3-jest27? What do you think is the best way to handle this?

[lmiller1990]

I think we should only support Jest 26 now, right, since we specify "version":" "26.0.0"`.

[nogic1008]

Changed to 26.x.

[nogic1008]

@lmiller1990
I think it's appropriate to separate the branches depending on supported Jest version.

• master branch
  • vue2-jest@latest (27.x)
  • vue3-jest@latest (27.x)
• 26.x branch
  • vue2-jest@26
  • vue3-jest@26

[lmiller1990]

@nogic1008 I see. I wonder if there will be any complexity in having both Vue 2 and Vue 3 in the same monorepo? Are we able to do this (I guess we need to do nohoist?)

Is there anything else you'd like to do before merging this? Otherwise, I'll merge and do a release to make sure everything is 👌 . Then we can work on getting Jest 27 support merged.

[nogic1008]

I believe that the complexity of including different Vue version in node_modules is less than the complexity of having to separate the same issues on different branches. (ex. security update by dependabot)
I copied /packages and /e2e from next branch to master branch locally, but it seems that nohoist settings are not needed at this time.

We need to merge next branch into master branch to complete the monorepo.
README also needs to be added and updated. (in root and each packages)

[lmiller1990]

Ok, let's try your idea.

I think we can update the README later, next goal should be Jest 27.

So we won't need next anymore - we will just have master for both Vue 2 and Vue 3.