Support content_for "block" named argument completion

[charlespwd]

This one is a bit harder because you need to change the parser and accept placeholder args in placeholder mode.

I'll leave that one for our team.

We want named argument completion:

{% content_for "block", █ %} -> `type`, `id`
{% content_for "block", ty█ %} -> `type`
{% content_for "block", i█ %}  -> `id`

Optional: complete closest.* arguments. Ask @mbarak for details :D

{% content_for "block", closest.█ %} -> `closest.product`, ...

Note

content.* is changing to closest.* after BFCM code freeze is lifted.

[mbarak]

"context" attributes are also supported in {% content_for "blocks" %} (blocks plural as opposed to block singular in the description). This variant doesn't accept id and type arguments but does support "context" attributes/arguments (like the singular block variant).

The supported context arguments are:

• context.<core_resource> ex: context.product
• context.metaobject.<metaobject type> ex: context.metaobject.123-metaobject_type

See here for more details:

https://github.com/Shopify/shopify/blob/9656f8a63a44c4be1d63f68a28bd3af109e5ecd0/areas/core/shopify/components/online_store/app/liquid/tags/content_for/block_strategy.rb#L9-L17