Add flat recommended config

[BPScott]

Fixes #591.
Fixes #592.
Original ideas extracted from #592.

Add flat recommended config file. Unlike the legacy recommended file this only enables the prettier rule and disables arrow-body-style and arrow-body-style. It does not enable anything from eslint-config-prettier.

It is now the responsibility of the consumer to enable both eslint-plugin-prettier and eslint-config-prettier. Configs extending other configs is complicated and not transparent. We should trust the user to configure their configs directly. In a future major change we should remove eslint-config-prettier from the legacy config too, as over lap between the responsibilities of eslint-plugin-prettier and eslint-config-prettier have always been a bit confusing and "a plugin goes and enables configs from other plugins" feels a bit odd. I think it is simpler if we push consumers towards "you configure both eslint-plugin-prettier and eslint-config-prettier in your repo's linting config.

Use it like this:

// eslint.config.js
const eslintPluginPrettierRecommended = require('eslint-plugin-prettier/recommended');
const eslintConfigPrettier = require('eslint-config-prettier');

return [
  eslintPluginPrettierRecommended,
  eslintConfigPrettier,
]

[changeset-bot]

🦋 Changeset detected

Latest commit: 3f05f8b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
eslint-plugin-prettier	Minor

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[BPScott]

@JounQin, @filiptammergard I've extracted the ideas from what we discussed in #592, and have rewritten the README to talk about the legacy vs new flat config.

I've dropped talking about "how to configure the plugin without using a config as I feel that just confuses people - the other plugins I've looked at all talk about leveraging configs first and only.

[BPScott]

@JounQin Thanks for the productive discussion. I've updated this PR so that the flat recommended config continues to extend from eslint-config-prettier. I've rerequested a review.

[JounQin]

@BPScott Thanks for accepting my proposal, and your writing is always impressive, I'm learning how to write such clear document from you as always!

[JounQin]

Thanks for addressing my nitpicking! Great work!