Fix compatibility issues with ESLint 9

[net]

ESLint 9 dropped support for some legacy plugin APIs. This migrates the plugin's rules to support ESLint 9, while staying backwards compatible.

Much of the diff is whitespace changes migrating legacy function rules to the object syntax, so I suggest viewing it with hide whitespace enabled.

Notably, this does not update the plugin to use the new flat config. This plugin will still work with the new flat config, but anyone wanting to use this in a flat config will have to use this compatibility syntax:

import relay from 'eslint-plugin-relay';

export default [
  // ...
  {
    plugins: { relay },
    // Note the default version on npm is a few years out of date, so to use
    // ts-recommended you have to install the latest @main tag via 
    //
    //     npm i --save-dev eslint-plugin-relay@main
    //
    rules: relay.configs['ts-recommended'].rules,
  },
];

If anyone wants to try updating the plugin to work natively with the new flat config, see: https://eslint.org/docs/latest/extend/plugin-migration-flat-config

Partially fixes #156.

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[tyao1]

Thanks for fixing compatibility issues! There are some lint error in the commit, could you take a look?

Run yarn run lint
yarn run v1.22.22
$ eslint eslint-plugin-relay.js src

/home/runner/work/eslint-plugin-relay/eslint-plugin-relay/src/rule-compat-uses-vars.js
  38:[4](https://github.com/relayjs/eslint-plugin-relay/actions/runs/13423081297/job/38121857195?pr=157#step:5:5)4  error  Parsing error: Unexpected token ?

/home/runner/work/eslint-plugin-relay/eslint-plugin-relay/src/rule-generated-flow-types.js
  88:42  error  Parsing error: Unexpected token ?

/home/runner/work/eslint-plugin-relay/eslint-plugin-relay/src/rule-generated-typescript-types.js
  332:44  error  Parsing error: Unexpected token ?

/home/runner/work/eslint-plugin-relay/eslint-plugin-relay/src/rule-graphql-naming.js
  [5](https://github.com/relayjs/eslint-plugin-relay/actions/runs/13423081297/job/38121857195?pr=157#step:5:6)9:54  error  Parsing error: Unexpected token ?

/home/runner/work/eslint-plugin-relay/eslint-plugin-relay/src/rule-graphql-syntax.js
  47:31  error  Parsing error: Unexpected token ?

/home/runner/work/eslint-plugin-relay/eslint-plugin-relay/src/utils.js
  48:48  error  Parsing error: Unexpected token ?

✖ [6](https://github.com/relayjs/eslint-plugin-relay/actions/runs/13423081297/job/38121857195?pr=157#step:5:7) problems (6 errors, 0 warnings)

[net]

@tyao1 I believe those are caused by the version of eslint that this repo itself uses being out of date. I’ll go ahead and update it to the latest if that works for you.