TSLint -> ESLint - Indent indent/tabs rule broken

[BurtHarris]

TSLint has been deprecated in favor of ESLint. See https://eslint.org/blog/2019/01/future-typescript-eslint#top. There seems to be a good migration path, e.g. https://code.visualstudio.com/api/advanced-topics/tslint-eslint-migration.

In trying this on the antlr4ts code base, I ran into a known problem: typescript-eslint/typescript-eslint#1824! Itsounds the indent rule for typescript is broken and hard to fix.

My proposal will be to disable the indent rule in ESLint, and use a dedicated code formatter, Prettier, to address standardizing indentation etc.

@sharwell is there a good reason we've got tab-based indents?

See palantir/tslint#4534 for further info on TSLint, it seems they are no longer even accepting PRs.