Update ESLint config, migrate some rules away from TSLint

[adidahiya]

Changes proposed in this pull request:

• Enable ESLint sort-imports rule, apply auto fixer to re-sort import statements
• Enable ESLint @typescript-eslint/no-extraneous-class rule
• Migrate TSLint variable-name -> ESLint @typescript-eslint/naming-convention rule
• Disable TSLint only-arrow-functions rule (already covered by ESLint prefer-arrow-callback)

This leaves just no-submodule-imports and object-literal-sort-keys enabled in the TSLint config. There are no equivalent lint rules out there that do exactly what we want here, so we'll have to implement some new rules ourselves if we want to fully migrate away from TSLint.

See typescript-eslint/ROADMAP.

[blueprint-bot]

lint fix

Previews: documentation | landing | table | demo