tools: auto fix custom eslint rule for buffer-constructor.js

[shobhitchittora]

This implements an es-lint fixer method to fix the usage of Deprecated Buffer() constructor.

Also adds some more test cases to the eslint rule.

Refs: #16636

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• commit message follows commit guidelines

Affected core subsystem(s)

Tools

[starkwang]

The new Buffer(size) is not equivalent to Buffer.from(...):
https://nodejs.org/dist/latest-v8.x/docs/api/buffer.html#buffer_buffer_from_buffer_alloc_and_buffer_allocunsafe

[shobhitchittora]

@starkwang So if I understand correctly, if the argument to Buffer constructor is number, then Buffer.alloc(size) should be used. Otherwise Buffer.from() can be used.

PS: Thanks for pointing it out.

[jasnell]

I'm a bit less keen on having an auto fix for this one, at least not yet. Which of the new constructors is used depends entirely on the type of input, which is not always clear. It's also important to consider between Buffer.alloc() and Buffer.allocUnsafe().

[apapirovski]

I don't think we need an auto-fixer for every lint rule. This one is a bit ambiguous so I tend to agree with @jasnell

[shobhitchittora]

@jasnell +1 that. Should I close this PR then?

[jasnell]

Yeah, let's close this one... just please don't let that discourage you! This work is very appreciated!