[heft-lint-plugin] Add support for ESLint 9

[D4N14L]

Summary

• Adds support for ESLint 9 to the @rushstack/heft-lint-plugin.
• Add new flat configs into @rushstack/eslint-config
• Creates new eslint-9-test project to test the plugin against ESLint 9
• [TODO] Updates projects that use the repo version of the ESLint plugin and configs to consume the new flat configs
• [TODO] Adds ESLint 9 support to eslint-bulk-suppressions

NOTE: Once merged, a publish and bump of decoupled dependencies will be required to update the remaining projects. The new configs should be moved into the decoupled rig, which currently is the source for the configs for the local-node-rig configs.

How it was tested

This PR.

Impacted documentation

Any ESLint-related docs will need to be updated to indicate support.

[benjamind]

What would it take to get this over the finish line? Am setting up a new repository with eslint today and would like to use eslint 9 if I can to avoid having to look at this again in a few months time :)

[D4N14L]

What would it take to get this over the finish line? Am setting up a new repository with eslint today and would like to use eslint 9 if I can to avoid having to look at this again in a few months time :)

The PR is in a workable state, though it needs reviews. It's... quite a large PR though, so it's (reasonably) taking some time for people to get around to it. Once I have some reviews, I'll merge in the latest changes in the repo and update to address feedback.

CC @IanC , @dmichon-msft