tools: enforce no unused trailing arguments tools directory

Use linting to enforce that the final argument for a function must be
used.

PR-URL: #16953
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>

Author: Trott

tools/.eslintrc.yaml

@@ -0,0 +1,4 @@
+rules:
+  # Variables
+  # http://eslint.org/docs/rules/#variables
+  no-unused-vars: [error, { args: 'after-used' }]