CI and Nx lint UI packages

[Peeja]

Currently, the lint tasks are disabled for the upload-service packages under packages/ui. ESLint is having trouble with some version mismatches with some very old config dependencies and sub-dependencies. Meanwhile, ESLint also has a whole new config system (flat config), and the one we're using (and our config dependencies use) is deprecated.

The best path here is probably to rebuild the config from scratch, using flat config, looking at the current config and extensions as reference. We should also make that config standard across all packages in the repo, with minor exceptions where there's some good reason.