Feature/preset block settings completion

[aswamy]

What are you adding in this PR?

Fixes #623

• Added support for presets blocks settings completion + hover
• Should work for deep-nested blocks within presets

Testing

• Checkout repo + branch + F5
• In the test VScode window, open a theme with presets & blocks
• Create a section/block that references a block
  • Add presets for the referenced block, and configure some of its settings (see tests / ticket description for more concrete examples)

example:

{% schema %}
{
  "name": "Example",
  "tag": null,
  "blocks": [{ "type": "@theme" }, { "type": "@app" }],
  "settings": [],
  "presets": [
    {
      "name": "Example Preset 1",
      "blocks": [
        {
          "type": "<referenced-block-name>",
          "settings": {
            "█"
          }
        }
      ]
    }
  ]
}
{% endschema %}

What's next? Any followup issues?

Pickup remaining tasks under #545

Before you deploy

• I included a minor bump changeset
• My feature is backward compatible