Handle deprecated rules (closes #112)

[alexilyaev]

• Conditionally add deprecated rules based on environment variable

Can now pass an environment variable to tell eslint-config-prettier not to add deprecated rules.

ESLINT_CONFIG_PRETTIER_NO_DEPRECATED=1 npx eslint-find-rules -d .eslintrc

Details

• See issue Handle deprecated rules #112
• Reasoning and alternatives: Handle deprecated rules (closes #112) #120 (comment)

[lydell]

Nice!

Now need to add:

• A test.
• Documentation. I think we could add a new sub-heading under Installation. At the end of the Installation section to be specific. Maybe "Excluding deprecated rules". That section would need to explain that eslint-config-prettier turns off a couple of deprecated rules and that that is nothing to worry about usually. Then we could mention the eslint-find-rules use case.

[alexilyaev]

@lydell I think I'm done.
The test was a bit tricky, see comments in my code.

[lydell]

Thanks! I’ll get back to you this weekend.

[alexilyaev]

@lydell Cool, I like the the updates you've made.