Introduce shopId in browserSession to set shop tenant

[alanko0511]

This PR introduces a new property in browserSession, shopId, that allows apps like Shopify theme app extensions to set up a session with a Shopify tenancy.

This allows use cases like fetching publicly accessible data for the specific shop without manually passing in the shop ID.

This PR also allows setting authentication modes at the top level, i.e. no need to declare the modes under the authenticationMode.

Click here to see an example usage

Example usage:

<!-- In extensions/theme-extension/blocks/star_rating.liquid -->
<script src="https://shop-auth-mode--development.ggt.pub/api/client/web.min.js" defer="defer"></script>
<script>
document.addEventListener("DOMContentLoaded", function () {
  const client = new Gadget({
    browserSession: {
      shopId: {{ shop.id }},
    },
  });

  client.getCurrentShop().then((result) => {
    const shopInfoElement = document.getElementById("shop-info");
    shopInfoElement.innerHTML = JSON.stringify(result, null, 2);
  })
})
</script>

<pre id="shop-info"></pre>

Then the shopInfoComponent should render the payload from the getCurrentShop global action with the current shop's data.

PR Checklist

• Important or complicated code is tested
• Any user facing changes are documented (changelog section below)
• Any app Problems are added to the problem finders
• Any app data that needs a redeploy to take effect is listed in the contentHash functions
• Important or complicated production behaviour has traces and logs added

Changelog

If this PR will affect change user-facing behaviour, add detailed information about the change here to prompt an AI generated changelog entry.

If no changelog is required, write [no-changelog-required] in square brackets [].

[infiton]

looks good; mind adding some type tests to make sure we have type errors if more than one option is passed

[MillanWangGadget]

looks reasonable 👍

[infiton]

looks good I think you can ship this one first; you'll need to cut a new release