Upgrade ESLint to the Latest Version

[kraftp]

This requires redoing our configuration files to their new flat format. More details here: #477

[devhawk]

Looks like this is a dupe of #442 and/or #458.

COmment from #465:

Note, I looked at moving over to the new config format as per #442, but couldn't figure out how to configure the linter without creating 100s of new lint errors. We can handle that in a separate PR

[devhawk]

I think upgrading to eslint 9 will have to wait for ts-eslint 8 to ship: https://typescript-eslint.io/blog/announcing-typescript-eslint-v8-beta

[kraftp]

Duplicate of #458