When I updated the ESLint plugin to support version 9, I did so in only

the most minimal way. This ended up requiring that consumers install an

additional package (@eslint/eslintrc) and use FlatCompat in their

configurations.
This change updates our plugin to actually be a modern plugin with

modern shared configuration:

Each of our predefined config layers is itself a flat config.
Configs are exported as plugin.configs.XXX.
Our cascading glob configs have been updated to use **/..., which makes

  it properly detect said files no matter where they are. This means we no

  longer have to do things like unversally include tests globals, since

  the jasmine block will be loaded when its supposed to be.
Moved some things from devDependencies to dependencies to reduce

  what consumers have to install themselves.

There are also some changes to the build process:

Use rollup instead of invoking babel directly.
Provide ESM and CJS exports in addition to UMD.
Generate and provide type definitions.

I've also made a couple tweaks to the rules themselves:

Added some additional stuff to indent ignore rules to avoid issues

  with complex generic class definitions.
Switch ES6 quotes rule to use @stylistic/quotes.
Add a configuration for @typescript-eslint/no-unused-vars to match

  the JS one, and added underscore prefixes to allow us to ignore things

  even that aren't parameters or locals (for example, inside TS generic

  definitions).
Fixed links to @stylistic docs to link to the latest docs instead of

  an older version that we weren't even using.

Built the plugin.
Used this from all of our other packages.