Allow disabling camelcase rule for class members

[jthomerson]

@pbredenberg I think we can address this long-standing issue with our linting rules now that [1] is closed.

Example of problem we encounter constantly because of our static class member naming convention:

public static from_buffer(b: Buffer, startingOffset: number): Foo { // eslint-disable-line camelcase

[1] typescript-eslint/typescript-eslint#590

[jthomerson]

CC @jimjenkins5

[pbredenberg]

@jthomerson @jimjenkins5 @yokuze

I created a PR on @silvermine/eslint-config with this implemented