Update prettier (gatsbyjs#22520)

* Update prettier to latest version

* Run 'yarn format' from root of project

* Remove prettier-ignore for nested markdown

* Fix starters

* Fix benchmarks

* Fix examples

* Fix integration-tests

* Update eslint-config-prettier & eslint-plugin-prettier

* Fix linting

* Update all .prettierrc

* Run Prettier on full codebase

* Remove unnecessary .prettierrc & .prettierignore files

* Update Prettier script

* Update snapshots

* Revert snapshot

* Revert "Update Prettier script"

This reverts commit 008eb99

* Update snapshot

* Update docs/blog/2018-08-09-swag-store/index.md

Co-Authored-By: Dima An <dmitriym44@gmail.com>

Co-authored-by: Dima An <dmitriym44@gmail.com>

.prettierrc

@@ -1,7 +1,4 @@
 {
-  "endOfLine": "lf",
-  "semi": false,
-  "singleQuote": false,
-  "tabWidth": 2,
-  "trailingComma": "es5"
+  "arrowParens": "avoid",
+  "semi": false
 }

package.json

@@ -19,7 +19,7 @@
     "react-helmet": "^5.2.1"
   },
   "devDependencies": {
-    "prettier": "^1.19.1"
+    "prettier": "2.0.4"
   },
   "keywords": [
     "gatsby"

yarn.lock

@@ -9666,10 +9666,10 @@ prepend-http@^2.0.0:
   resolved "https://registry.yarnpkg.com/prepend-http/-/prepend-http-2.0.0.tgz#e92434bfa5ea8c19f41cdfd401d741a3c819d897"
   integrity sha1-6SQ0v6XqjBn0HN/UAddBo8gZ2Jc=
 
-prettier@^1.19.1:
-  version "1.19.1"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.19.1.tgz#f7d7f5ff8a9cd872a7be4ca142095956a60797cb"
-  integrity sha512-s7PoyDv/II1ObgQunCbB9PdLmUcBZcnWOcxDh7O0N/UwDEsHyqkW+Qh28jW+mVuCdx7gLB0BotYI1Y6uI9iyew==
+prettier@2.0.4:
+  version "2.0.4"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-2.0.4.tgz#2d1bae173e355996ee355ec9830a7a1ee05457ef"
+  integrity sha512-SVJIQ51spzFDvh4fIbCLvciiDMCrRhlN3mbZvv/+ycjvmF5E73bKdGfU8QDLNmjYJf+lsGnDBC4UUnvTe5OO0w==
 
 pretty-bytes@^5.1.0, pretty-bytes@^5.3.0:
   version "5.3.0"