Upgrade Vuepress, Flow, and misc

[AtofStryker]

The goal of this PR is to update some out of date dependencies in the workspace. The two largest upgrades, relatively, in this PR are flow and vuepress.

VuePress ee2140d

The version of vuepress was really out of date on version 0.x. Keeping the version at 0.x has caused a lot of issues around other upgrades or build dependencies, especially when performing #1628 and #1629 .

I followed the upgrade guide to get us to 1.x. Because of significant babel/loader issues with the older versions of vuepress, the lock file needed to be deduped in ee2140d. A removal of node_modules locally will likely be necessary as well as a reinstall. Otherwise, you might run into issues with babel or cache-loader

There are also some changes with the theme styling:

VTU Documentation: Production

Vue Documentation: Production

VTU Documentation: Changeset ee2140d

Font is noticeably bigger on the nav and nav drawer (and in some cases, in general)

Flow 2328676

Flow is currently very out of date at version 66. Keeping flow up (v133) to date will allow us to get newer features and security/bug fixes. On my end, my flow vscode extention doesn't seem to like the old version, so actually utilizing flow in editor is a bit painful.

The largest change here for us is the removal of the suppress comment option, as $FlowIgnore and others are now supported/suppressed by default. A few $FlowIgnores had to be added to the code to keep suppression behavior consistent. See https://flow.org/en/docs/config/options/#toc-suppress-comment-regex for more
details.

Core-js cc869b9

We only use core-js currently within our testing pipeline to run our components in the browser. 2 Is currently deprecated and upgrading was blocked due to some babel issues with older versions of vuepress. See https://babeljs.io/docs/en/babel-preset-env#corejs for more details.

Chalk 5f7ee1e

Since the API signature has not changed for our usage, we can bump chalk to 4.x without changing anything.

Typescript 8a74e52

Pinning typescript to ^3.9.7 helps fit in with the rest of the style of the repository, as well as making it a bit clearer as to which/what type of verison of TS is installed. Previously installed in the lock was 3.7.2

Cross-Env 1e85372

Since cross-env 7 has the same signature, but published a major version for no longer supporting Node < 10.x, an upgrade here should be safe.

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• It's submitted to the dev branch.
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• All tests are passing: https://github.com/vuejs/vue-test-utils/blob/dev/.github/CONTRIBUTING.md#development-setup
• New/updated tests are included

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information:

[AtofStryker]

@lmiller1990 I went ahead and rebased this guy too. Let me know if there is too much going on is this PR. The changeset is the same for the commits referenced in the description, but I can update those if you need me to.