1. Bumped eslint and its plugins versions, and autofix new errors (mostly eslint disables which were no longer neccessary)
2. ~~Replace eslint with eslint-p which speed up linter a bit (at least on my machine)~~ - CI machines don't like it.
3. Fixed/worked around one problem with flacky selection _unit_ tests.
Fixes#10668Fixes#8484
Summary of changes:
* `gui2` and `dashboard` are merged to `gui` directory. Various configs were merged (package.json, playwrigth, TS...). The src and e2e directories are split to `dashboard` and `project-view` for now.
* E2E tests run two servers on different ports. The tests are organized in projects. This is also to be changed soon, as we plan to [use better mocking in GUI/ProjectView](#9726)
* ESlint configs were merged to central `eslint.config.mjs`, and that file was moved to repository root. We kept the dashboard lints, but they can be relaxed. The dashboard code was changed to meet GUI lints.
* Also, the versions of linter plugins were bumped, and code fixed.
* The ide-desktop/client no longer has `dashboard` dependency - the only type used there was moved to common package.
* `common` package moved to `app`.
