Change spaces to tabs in json files

[simison]

Tabs everywhere makes more sense given the rest of the codebase.

Spaces in package.json seem to be there for historic reasons; NPM enforced them until NPM v5 and nowadays NPM doesn't care.

Recently did the same in Calypso: Automattic/wp-calypso#31543

Next up: run json files with Prettier in pre-commit hook:

jetpack/bin/pre-commit-hook.js

Line 88 in 8ba0941

`./node_modules/.bin/prettier --ignore-path .eslintignore --write ${ toPrettify.join( ' ' ) }`

That Prettier implementation will anyway need some work with #11633

Changes proposed in this Pull Request:

• :tab: -> :space:

Testing instructions:

Everything should stay as is. 🎉 🌮

[simison]

Note that .jshintrc file was already using tabs...

[simison]

Hmm, actually I could close this since #11507 already does the same for these files. @sirreal I was mostly interested to change .editorconfig here — mind bringing that change to your Prettier PR?

[jetpackbot]

	Warnings
⚠️	"Proposed changelog entry" is missing for this PR. Please include any meaningful changes

This is an automated check which relies on PULL_REQUEST_TEMPLATE. We encourage you to follow that template as it helps Jetpack maintainers do their job. If you think 'Testing instructions' or 'Proposed changelog entry' are not needed for your PR - please explain why you think so. Thanks for cooperation 🤖

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[sirreal]

mind bringing that change to your Prettier PR?

Sounds great to me 👍