The only thing I didn't do is change the `package.json` `name`, since
that would also change the VSCode extension name. But `solidity` is
taken on NPM, so you'll need to temporarily change the name each time
you run `npm publish` and then change it back.

Publish to NPM: `npm publish`

Users:
```
npm install -g @juanfranblano/vscode-solidity-server
vscode-solidity-server --stdio
```

This PR does two things to make this possible:
- adds "files" and "prePublishOnly" to `package.json` to use `tsup`
- updates `server.ts` to read the default config from `package.json` so
  that even if the client doesn't send a config, they'll still get the
  default behavior. This is because if the non-VSCode client has to keep
  manually copying the client config from `package.json`, it's hard to keep it
  up-to-date.