Adds prettier as local dependency.

package.json

@@ -13,5 +13,8 @@
 		"build-extension": "yarn workspace debug-visualizer build",
 		"build-visualization": "yarn workspace @hediet/visualization build",
 		"build-ui": "yarn workspace debug-visualizer-webview build"
+	},
+	"devDependencies": {
+		"prettier": "^1.19.1"
 	}
 }

yarn.lock

@@ -7690,6 +7690,11 @@ prepend-http@^1.0.0:
   resolved "https://registry.yarnpkg.com/prepend-http/-/prepend-http-1.0.4.tgz#d4f4562b0ce3696e41ac52d0e002e57a635dc6dc"
   integrity sha1-1PRWKwzjaW5BrFLQ4ALlemNdxtw=
 
+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==
+
 pretty-error@^2.0.2:
   version "2.1.1"
   resolved "https://registry.yarnpkg.com/pretty-error/-/pretty-error-2.1.1.tgz#5f4f87c8f91e5ae3f3ba87ab4cf5e03b1a17f1a3"