feat(eslint-plugin): support ESLint v9 (and v8)

[timdeschryver]

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/ngrx/platform/blob/main/CONTRIBUTING.md#commit
• [x] Tests for the changes have been added (for bug fixes / features)
• [x] Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[x] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Closes #4365

What is the new behavior?

Does this PR introduce a breaking change?

[x] Yes
[ ] No

BREAKING CHANGE:

The configuration of several rules are changed, making the rules more strict (warnings became errors).
Configuration names are renamed to be more clear and follow the naming convention of other plugins.
For an overview of the configuration rules and available configurations see https://ngrx.io/guide/eslint-plugin.

Other information

After this PR, #4299 can be picked up. The docs still need to be updated, which is something I plan to do in the next days/weeks.

Some highlights:

Public:

• Supports ESLint v9 flat config as opt-in (available through @ngrx/eslint-plugin/v9)

const eslint = require("@eslint/js");
const tseslint = require("typescript-eslint");
const angular = require("angular-eslint");
// 👇
const ngrx = require("@ngrx/eslint-plugin/v9");

module.exports = tseslint.config(
  {
    files: ["**/*.ts"],
    extends: [
      eslint.configs.recommended,
      ...tseslint.configs.recommended,
      ...angular.configs.tsRecommended,
      // 👇
      ...ngrx.configs.recommended,
    ],
    processor: angular.processInlineTemplates,
);

• Still support ESLint v8 syntax
• Remove requiring-type-checking configurations, instead these are replaced with recommended (without type checking and thus faster) and all (including a few type requiring rules) configurations. This makes the configuration simpler.

Internal:

• migrate @typescript-eslint/experimental-utils to @typescript-eslint/utils
• remove eslint-etc: this library has become outdated (and some types were conflicting due to this)
• update @typescript-eslint
• reflect changes to types/config in generation scripts (for docs)

It works 🎉 Left: ESLint v9 Right: ESLint v8

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