Add support for webc:bucket on any tag, cascade to all child content

[zachleat]

This is related to the Asset Bucketing feature, webc:bucket: https://www.11ty.dev/docs/languages/webc/#asset-bucketing

Currently this attribute only works on style, link rel="stylesheet", or script. This would allow authors to add this attribute to any element and would apply the bucket value to any child content in the tree under the node.

Furthermore, also add a hoisting feature to de-duplicate content that is added to multiple distinct buckets.

For example:

<div webc:bucket="inherited-bucket">
    <component></component>
    <component webc:bucket="my-bucket-override"></component>
</div>

• <component></component> has an inherited bucket value of inherited-bucket
• <component webc:bucket="my-bucket-override"></component> has a bucket value of 'my-bucket-override' but this is ignored.
• The closest bucket value that works for both <component> instances is used, in this case inherited-bucket.

Another example:

<component></component>
<component webc:bucket="my-bucket-override"></component>

• <component></component> has an implied bucket value of default
• <component webc:bucket="my-bucket-override"></component> has a bucket value of 'my-bucket-override' but this is ignored.
• The closest bucket value that works for both <component> instances is used, in this case default.

Another example:

<component webc:bucket="my-bucket-override"></component>
<component webc:bucket="my-bucket-override"></component>

• <component webc:bucket="my-bucket-override"></component> both have a bucket value of 'my-bucket-override' and it is used.

Marginally related to 11ty/eleventy-plugin-bundle#5