Help.js port to ES6

[ricknjacky]

In continuation of #2656

and part of fix as proposed in #2609
js/widgets/help.js is now completely cleaned up.

[ricknjacky]

Although the file is ported to ES6 syntax, the linting for some part of the code seems erratic.

This is in reference to conversation thread on #2609
Where @walterbender suggested that

if (
foo &&
bar
) {

is a particularly annoying one.

and

I'd prefer:

if (foo &&
bar) {

So, should I change this file for the same?

[ricknjacky]

PS:- I am addressing the way let label is declared and not the if statement

[meganindya]

Linting and formatting are different things for the most part. Not really bothering about that on this codebase anymore. There are thousands of issues re those.

[meganindya]

LGTM