Remove gulp-flowtype Dependency

Summary:
[BizSDK][NodeJS] Remove gulp-flowtype Dependency

This dependency is deprecated and no longer used.
In the future we would like to evaluate if gulp itself is still needed in our project.

Differential Revision: D48919251

fbshipit-source-id: ed8edc572c47c283710519db7fa5c173f9cc6673

.flowconfig

@@ -5,9 +5,7 @@
 .*src/objects/serverside
 .*src/objects/signal
 <PROJECT_ROOT>/node_modules/resolve/test/resolver/malformed_package_json/package.json
-# need to address this issue in gulp-flowtype
-<PROJECT_ROOT>/node_modules/gulp-flowtype/lib/index.js
-<PROJECT_ROOT>/node_modules/gulp-flowtype/index.js
+
 [include]
 
 [libs]

package.json

@@ -55,7 +55,6 @@
     "gulp": "^4.0.2",
     "gulp-cli": "^2.2.0",
     "gulp-filenames": "~4.0.0",
-    "gulp-flowtype": "^1.0.0",
     "gulp-load-plugins": "^1.6.0",
     "gulp-open": "^3.0.1",
     "gulp-rename": "^1.2.3",