Support static files

[noelklein]

I used npm init @open-wc to generate a new project. Here I can't use this prebuilt version to output static files with storybook. According to the storybook cli docs I can use -s public to include folders with static assets like images but this doesn't work with your cli.

Storybook CLI docs: https://storybook.js.org/docs/ember/configure/images-and-assets#serving-static-files-via-storybook

Desired functionality:

"storybook:build": "tsc && build-storybook -s public"

Error logs:

mej440@3c22fb0e0c3d some-inventory % yarn storybook:build
yarn run v1.22.10
$ tsc && build-storybook -s public
(node:17178) UnhandledPromiseRejectionWarning: UNKNOWN_OPTION: Unknown option: -s
    at Object.commandLineArgs [as default] (/Users/mej440/Documents/GitHub/asdf/some-inventory/node_modules/command-line-args/dist/index.js:1347:21)
    at main (/Users/mej440/Documents/GitHub/asdf/some-inventory/node_modules/@web/dev-server-storybook/dist/build/cli.js:11:45)
    at Object.<anonymous> (/Users/mej440/Documents/GitHub/asdf/some-inventory/node_modules/@web/dev-server-storybook/dist/build/cli.js:35:1)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
    at Module.load (internal/modules/cjs/loader.js:928:32)
    at Function.Module._load (internal/modules/cjs/loader.js:769:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
    at internal/main/run_main_module.js:17:47
(Use `node --trace-warnings ...` to show where the warning was created)
(node:17178) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:17178) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
✨  Done in 4.86s.
mej440@3c22fb0e0c3d some-inventory %