Add prettier, configs and editorconfig

.editorconfig

@@ -0,0 +1,15 @@
+# editorconfig.org
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+indent_style = space
+insert_final_newline = true
+max_line_length = 250
+trim_trailing_whitespace = true
+
+[*.{js,json}]
+indent_size = 4
+indent_style = tab