Support for eslint v9

[hughns]

I don't know what exactly needs doing but I have encountered that the configuration file structure has changed: https://eslint.org/docs/latest/use/configure/migration-guide

[robintown]

It looks like the most recent release of this plugin is broken as it now requires eslint-plugin-unicorn >= 57 (#45), which only supports eslint v9

[t3chguy]

The web team has agreed to abandon eslint due to the v9 mess, currently (somewhat) evaluating biome https://github.com/element-hq/element-desktop/pull/2214/files