feat: add eslint support

[davelsan]

Issue

Related to graphql-server-model-codegen #150.

Description

Added support for ESLint.

Implementation

The eslintrc config extends eslint:recommended, with a few additions / modifications:

• The parser is set to use babel-eslint.
• Standard rules for indent, linebreak-style, quotes, and semi have been set.
• Rule no-unused-vars has been set to warn for everything but function args.
• Code-generated folders are ignored using .eslintignore rules, except for the few files within that are provided statically.

Blocks

None.

Notes

• Using babel-eslint allows us to use features already supported by NodeJS latest (e.g. static-class-props). When Babel v8 is released this module will be deprecated in favor of @babel/eslint-parser. The migration will likely require a few additional configuration changes.