chore(dev-deps): upgrade babel, jest, eslint

[acao]

I think this might nip a few upstream babel issues I've started seeing in CI (github actions, netlify). I've disabled dependabot except for security updates, because of noise in the git log more than anything.

contains:

• changes from prettier 1.x to 2.x - arrow parenthesis is by default now so I disabled that in .prettierrc, however space between function ( as such is now required. Prettier migration notes
• upgrade babel and dependencies - to fix some build issues seen in GA and netlify
• add prettier-ignore to markdown files where we tend to have issues (where users open PRs via github UI especially)

[codecov]

Codecov Report

Merging #1470 into master will not change coverage by %.
The diff coverage is 50.00%.

@@           Coverage Diff           @@
##           master    #1470   +/-   ##
=======================================
  Coverage   58.98%   58.98%           
=======================================
  Files          60       60           
  Lines        3023     3023           
  Branches      806      796   -10     
=======================================
  Hits         1783     1783           
  Misses       1194     1194           
  Partials       46       46           

Impacted Files	Coverage Δ
packages/graphiql/src/components/ImagePreview.tsx	2.85% <0.00%> (ø)
packages/graphiql/src/utility/debounce.ts	83.33% <100.00%> (ø)

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