Use the root typings for keytar since we are loading the root node module (#112718)

extensions/github-authentication/package.json

@@ -58,7 +58,6 @@
     "vscode-nls": "^4.1.2"
   },
   "devDependencies": {
-    "@types/keytar": "^4.4.2",
     "@types/node": "^10.12.21",
     "@types/node-fetch": "2.5.7",
     "@types/uuid": "8.0.0"

extensions/microsoft-authentication/package.json

@@ -38,7 +38,6 @@
 		"watch-web": "npx webpack-cli --config extension-browser.webpack.config --mode none --watch --info-verbosity verbose"
 	},
 	"devDependencies": {
-		"@types/keytar": "^4.0.1",
 		"@types/node": "^10.12.21",
 		"@types/node-fetch": "^2.5.7",
 		"@types/randombytes": "^2.0.0",