Add a "Migrating from ESLint" page

[connorshea]

This is intended for existing JavaScript/TypeScript projects that currently use ESLint and want to move to Oxlint to get overall better performance.

Cover the following main topics:

• Use @oxlint/migrate to migrate your ESLint flat config to an oxlint config with all supported rules ported over.
  • If you use typescript-eslint, ensure you pass the --type-aware flag to the migration script.
  • If you use plugins not supported natively in oxlint, use the --js-plugins flag to add them.
• If you're not on a flat file ESLint config, you may need to manually convert your config file.
• Alternatively, use oxlint-eslint-plugin to disable rules already supported by oxlint, and run both in CI until all rules you need have been ported to oxlint. (you can do both the migration script and this plugin, if desired)
• Similar misc notes to the prettier migration doc: Update relevant contribution docs, agents.md, CI configs, VS Code repo settings, recommended editor extensions, etc.