Enforce Prettier defaults + also format .babelrc and .json (#7499)

* .prettierrc: full configuration for Prettier

This way, contributors using different-from-default settings will still
use the correct prettier settings

* Makefile: also lint .babelrc.js

* Makefile: also prettify .json files

* Exclude package.json files and correct build dir

* Add more default options to prettierrc and load it in cli

This avoids prettier looking up the config for each file

* Format json

* Update prettier and eslint and reformat codebase

* Remove obsolete file

* Add comment

lerna.json

@@ -16,19 +16,10 @@
   "cacheDir": ".changelog",
   "commands": {
     "publish": {
-      "ignore": [
-        "*.md",
-        "test/**",
-        "codemods/**"
-      ]
+      "ignore": ["*.md", "test/**", "codemods/**"]
     }
   },
-  "packages": [
-    "packages/*",
-    "codemods/*"
-  ],
+  "packages": ["packages/*", "codemods/*"],
   "npmClient": "yarn",
-  "npmClientArgs": [
-    "--no-lockfile"
-  ]
+  "npmClientArgs": ["--no-lockfile"]
 }