chore(*): add node 14 to build matrices, desupport node 8

[sverweij]

Description, Motivation and Context

• De-supports node 8 (node 8 is not supported anymore by nodejs since the end of last year and many dependencies drop their node 8 support, so it's not sustainable to keep node 8 supported). This counts as a 💥 BREAKING CHANGE, so some bumping & branching will need to be done after merging this PR.
• Adds node 14 to the build matrices as the main platform to support
• Ups dependencies to latest (including those that were not updated because they de-supported node 8 earlier on in the year). This update includes an upgrade to prettier 2 and more recent versions of some aslant plugins, so most source files will have been reformatted.

How Has This Been Tested?

Green CI

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Documentation only change
• Refactor (non-breaking change which fixes an issue without changing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• 📖

  • My change doesn't require a documentation update, or ...
  • it does and I have updated it

• ⚖️

  • The contribution will be subject to The MIT license, and I'm OK with that.
  • The contribution is my own original work.
  • I am ok with the stuff in CONTRIBUTING.md.

[codeclimate]

Code Climate has analyzed commit 0dad358 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (99% is the threshold).

This pull request will bring the total coverage in the repository to 99.9% (0.0% change).

View more on Code Climate.