eslint 9 update

[kaisalmen]

The eslint configuration of open-collaboration-tools has been the baseline for this implementation. Specific adjustment from the old configuration have been added.

The TypeScript configuration has been clean and aligned with OCT as well.
I needed to lower the compiler target to ES2020 because otherwise almost half of the unit test using the chevrotain parser failed. The lib reference was lowered from ESNEXT to ES2020 as well to ensure lib and target are in-line. This required some code changes, because string.replaceAll is only available after ES2021.
This PR also bumps the minimum engines up to node 20. ES2022/ES2023 should be valid TS/node20 target according to this list from TypeScript, but it doesn't help if our dependency stacks doesn't work with (potential chevrotain issue/investigation required?).

All dependencies but yeoman-generator were updated to current versions, because of incompatible API changes. This should be tracked in a new issue.

One hack remains: I can't set 'no-useless-escape': 'off' inherited rule from eslint:recommended, although it should it work. 🤷‍♂️ It is taken into account, because once I configure an illegal string eslint does not start. I excluded the generated syntaxes/*.monarch.ts files from processing. The real cause /[/\*]/ (backslah not required) in the monarch generator should be fixed at one point, but still the config override must work. Update: I just saw those files were contained in the deleted eslintignore as well, so the problem is not new.

Fixes #1904
Fixes #1905

[Copilot]

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• .editorconfig: Language not supported
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• .vscode/settings.json: Language not supported
• examples/arithmetics/package.json: Language not supported
• examples/domainmodel/package.json: Language not supported
• examples/requirements/package.json: Language not supported
• examples/statemachine/package.json: Language not supported
• package.json: Language not supported
• packages/generator-langium/package.json: Language not supported
• packages/generator-langium/templates/cli/.package.json: Language not supported

Comments suppressed due to low confidence (2)

packages/generator-langium/src/index.ts:184

• The variable name 'path' shadows the imported Node 'path' module. Consider renaming it (e.g., 'targetPath') to avoid potential conflicts or confusion.

for (const path of ['.', '.vscode', 'eslint.config.mjs']) {

examples/statemachine/esbuild.mjs:1

• Removing the //@ts-check comment disables inline type-checking in this file; ensure that your build process or IDE still enforces the desired type safety.

-//@ts-check

[Copilot]

Copilot reviewed 36 out of 50 changed files in this pull request and generated no comments.

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• .editorconfig: Language not supported
• .eslintignore: Language not supported
• .eslintrc.json: Language not supported
• .nvmrc: Language not supported
• .vscode/settings.json: Language not supported
• examples/arithmetics/package.json: Language not supported
• examples/domainmodel/package.json: Language not supported
• examples/requirements/package.json: Language not supported
• examples/statemachine/package.json: Language not supported
• package.json: Language not supported
• packages/generator-langium/package.json: Language not supported
• packages/generator-langium/templates/cli/.package.json: Language not supported
• packages/generator-langium/templates/core/.eslintrc.json: Language not supported
• packages/generator-langium/templates/core/.package.json: Language not supported

Comments suppressed due to low confidence (3)

packages/generator-langium/templates/web/src/setupClassic.ts:13

• Replacing a template literal with a single-quoted string may remove future interpolation support. Verify that this change is intentional and that no dynamic content is expected.

code: '// <%= RawLanguageName %> is running in the web!',

packages/generator-langium/src/index.ts:184

• Ensure that the update from '.eslintrc.json' to 'eslint.config.mjs' correctly reflects your project's ESLint configuration file location and that all references to the old config are removed.

for (const path of ['.', '.vscode', 'eslint.config.mjs']) {

examples/requirements/src/cli/generator.ts:19

• Removing the eslint-disable directive for indent may reintroduce formatting issues if the ESLint indent rule is enforced; please confirm that the generated HTML content remains properly formatted.

/* eslint-disable @typescript-eslint/indent */

[kaisalmen]

Next time I will separate compiler update, eslint update and required dependencies into separate PRs. From the recent upgrade experience in OCT I thought this is an straightforward task, but larger code bases bring more complexity. I know that and should not fall into the trap. 🙂 Implementation becomes harder and the review as well. My apologies for making this review more complex than needed.