internal tooling: next steps for linters and formatter

[Galimede]

Formatter (Prettier)

• Study how we can develop plugins
• Make a list of formatting "rules" that are not convenient for us (e.g: ternary)
• Implement plugins to match our needs

Linter (ESLint)

• Check migration to version 9 feasibility
• Update plugins
• Migrate the config to the new file format
• Get rid of Prettier plugin as it will not be relevant anymore

[florian-sanders-cc]

@Galimede thanks for your awesome work, as discussed I'm just leaving a comment here to track what's blocking us from upgrading to ESLint@9.X.X after trying to do it:

• standardjs future is very uncertain and it's very unlikely the related eslint plugin will support v9 of ESLint (cf #1948 - standard repo. There's a new standard that seems to support it (cf neostandard repo),
• eslint-plugin-import does not support v9 for the moment. There's another plugin (which used to be a fork actually) that seems close to supporting it: eslint-plugin-import-x. It does work with v9 in our project but it's not official and they still have some work to do.
• Our custom rule i18n-no-paramless-arrow does not work anymore, we'll need to dig a bit more to check why. This is the only rule that broke, I've tested others and they still work :+1: