feat: auto detect the eslint.config.js file to enable flat config support

[sxyazi]

eslint/eslint@7162d34

ESLint's new config system is complete, this PR offers auto-detecting of the new config file in the project root, then set the experimental.useFlatConfig = true to enable it automatedly.

[glepnir]

Check out the documentation. This new configuration system defaults to false. It uses file and environment variables to control whether it is enabled. The environment variable ESLINT_USE_FLAT_CONFIG has higher priority. So shouldn't it be up to the user to control whether to enable or not. It should exist in the local configuration file. So I don't think it is necessary to add a check for this file by default right?

[sxyazi]

The ESLINT_USE_FLAT_CONFIG environment variable exists only in ESLint, but it is ESLint LSP, i.e. vscode-eslint.

AFAIK, it can only be turned on by setting experimental.useFlatConfig = true, there is no configuration file or environment variable available.

[polyzen]

ESLint itself uses eslint.config.js by default now if it's found.

Also for reference:
microsoft/vscode-eslint#1644

[sxyazi]

https://github.com/neovim/nvim-lspconfig/blob/32f0c0465ac3ee53a1a9c0f72602a7b9cecb31d3/lua/lspconfig/server_configurations/eslint.lua#L108C1-L111

🤔 The two lines also use / to join the paths, so it's problematic too?

[glepnir]

util.path has a santize function it will check is windows or not then convert \\ to /

[sxyazi]

The two lines above don't seem to call the sanitize, can you point out where it is? IMO Windows should also support /

[glepnir]

long time no used windows check wiki https://en.wikipedia.org/wiki/Path_(computing) looks like windows also accept the '/' so maybe just path_join is enough

[sxyazi]

Yeah, that's what I'm trying to say! I will revert the commit just made then.