tools: refactor for arrow callbacks and trailing commas

First commit:

tools: refactor tools JS code

* standardize on arrow functions for callbacks
* standaradize on trailing commas for multiline arrays

Second commit:

tools: apply stricter linting to tools directory

Enable ESLint rules for trailing commas and arrow callbacks in tools
directory. These rules are also in place in the benchmark directory.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines