ci: upgrade eslint v9

[kyranjamie]

In response to some lint errors in extension relating to eslint, and the drive towards esm, I tried to upgrade the monorepo to use their new flat format with v9.

It turns out the Expo native lint plugin doesn't work with v9 yet though, so this can sit here until ready.

[tigranpetrossian]

@kyranjamie It looks like the missing expo stuff is only a handful of settings + importing their own set of a general rules. We should be able to easily fork the necessary parts (excluding their internal rules) and make our own native preset. I still need to figure out the new flat config, will try to look into this when I get a chance.

[kyranjamie]

Thanks @tigranpetrossian, that'd be awesome. I jumped the gun doing this because v9 had only just come out. 9.x versions have all kind of migration tools etc, so should be easier now