Upgrade eslint

[wpessers]

What is the feature request about
We'd like to upgrade to the latest eslint 10.X.X version. But there are currently some conflicting dependency versions and use of old eslint config format that make this impossible.

Some prerequisite work that can be done in (a) separate pr(s)

• Evaluate whether eslint plugins eslint-plugin-header and eslint-plugin-import are still used, they are causing eslint version conflicts when trying to upgrade
• Upgrade eslint to version 9
• Upgrade gts to version 7
• Move to eslint flat config format

ESLint v10 upgrade
Before we can upgrade to eslint 10 we need to verify it's compatible with the gts library. If not evaluate if we want to inline these rules in the eslint config ourselves.

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[ritvick]

I intend to work on this issue

[wpessers]

@ritvick great! 🚀

[ritvick]

Evaluated that eslint-plugin-header is used in eslint config, but no rules are used, hence its safe to remove
Evaluated that eslint-plugin-import is not even used in eslint config, hence its safe to remove as well.
PR: #2170

[wpessers]

@ritvick any intentions to complete this work? there's quite some security advisories that would automatically disappear if we can upgrade this dev tooling for the nodejs layer.

[wpessers]

Took up the remaining changes since we don't want to drag this along any longer than necessary. Thanks for the assistance on the first steps!