- Ensure that `pdfjsTestingUtils` is available when running benchmarking, since that shouldn't be done in TESTING-mode.
- Exclude the `test/stats/results/` folder from linting, since it'll contain *generated* JSON-files.
Flat config is the new config system used by ESLint 9.
To make the migration easier, they also added
flat config support to ESLint 8.
This commit migrates the various ESLint configs in the repository to use
the new system, **without** upgrading to ESLint 9 yet.
