Update `.editorconfig` and `*.json` files to use tabs for indentation

[netweb]

When the .editorconfig file was added in [27198] it included the option to indent *.json files with 2 spaces, this was inherited from the jQuery projects .editorconfig

There's no inherent reason^(note) to require this, see ​https://stackoverflow.com/a/18698771/1911294

Originally discussed here ​https://github.com/WordPress/gutenberg/pull/1029#issuecomment-306362413

Note: An existing issue with npm 3 and 4 causes indentation issues, as such package.json needs to remain indented with spaces until WordPress chooses to use npm 5 as the required minimum.

[pento]

In 41835:

General: Remove .jshintrc and *.json from the 2-space-indent .editorconfig group.

JSON files don't need a particular indent style, this was just inherited from the jQuery .editorconfig, that we based ours on.

package.json is staying in the 2-space-indent group for now, due to npm 3 and 4 having issues. Upgrading to npm 5 will allow us to remove package.json, too.

Props netweb.
Fixes #40946.