coordinate linting of JS files in examples/* and .mjs files in the repo

[trentm]

Currently the linting in this repo works like this:

• npm run lint at the top-level runs npm run lint in each of the packages in the workspace
• these all run eslint using a shared "eslint.config.js" from the top-level (which includes the "prettier" plugin for style, including using the "prettier.config.js" at the top-level)

This issue is about:

1. Including JS and TS files in examples/..., linted via npm run lint and using the same shared config files. (Currently there is a npm run lint:examples, but it (a) is not run in CI and (b) uses a different eslint config ("examples/.eslintrc").
2. Linting JS files (in addition to the TS files that are already linted) elsewhere in the repo. There aren't many: mostly these are .../test/fixtures/*.mjs files for testing ESM instrumentation.

The plan is to:

• Update the eslint.config.js to support linting .js and .mjs files. Currently it just works for TS files.
  DONE in chore(eslint): lint examples/bunyan and prepare for linting .js and .mjs files #2567
• Work through each of the examples/* packages adding npm run lint and npm run lint:fix using the top-level shared eslint config file; and getting that lint passing.
  • examples/bunyan (chore(eslint): lint examples/bunyan and prepare for linting .js and .mjs files #2567)
  • examples/connect (chore(examples): lint examples/connect using shared top-level eslint config #2897)
  • examples/dns (chore(examples): lint examples/dns using shared top-level eslint config #2898)
  • examples/express (chore(examples): lint examples/express using shared top-level eslint config #2894)
  • examples/fastify (chore(examples): lint examples/fastify using shared top-level eslint config #2896)
  • examples/graphql (chore(examples): lint examples/graphql using shared top-level eslint config #2899)
  • examples/grpc-census-prop (chore(examples): lint examples/grpc-census-prop using shared top-level eslint config #2900)
  • examples/hapi (chore(examples): lint examples/hapi using shared top-level eslint config #2892)
  • examples/host-metrics (chore(examples): lint examples/host-metrics using shared top-level eslint config #2901)
  • examples/ioredis (chore(examples): lint examples/ioredis using shared top-level eslint config #2902)
  • examples/koa (chore(examples): lint examples/koa using shared top-level eslint config #2903)
  • examples/memcached (chore(examples): lint examples/memcached using shared top-level eslint config #2904)
  • examples/meta-node (chore(examples): lint examples/meta-node using shared top-level eslint config #2905)
  • examples/mongodb (chore(examples): lint examples/mongodb using shared top-level eslint config #2906)
  • examples/mysql (chore(examples): lint examples/mysql using shared top-level eslint config #2907)
  • examples/network (chore(examples): lint examples/network using shared top-level eslint config #2908)
  • examples/react-load/preact & examples/react-load/react (chore(examples): lint examples/react-load using shared top-level eslint config #2913)
  • examples/redis (chore(examples): lint examples/redis using shared top-level eslint config #2909)
  • examples/restify (I'm proposing we drop this example: chore(examples): drop examples/restify #2910)
  • examples/router (chore(examples): lint examples/router using shared top-level eslint config #2911)
  • examples/web (chore(examples): lint examples/web using shared top-level eslint config #2912)
• Add npm run lint:examples to the npm run lint that is run in CI. (chore(examples): lint examples/ using shared top-level eslint config; add lint:examples to 'npm run lint' #2919)
• Change npm run lint in the workspace packages to also lint .mjs (and maybe .js) files -- at least in packages that have JS files and not just TS files. chore: lint .js and .mjs files (in addition to the existing .ts file linting) #2940

(The original work for this started in #2567.)