Make Filter Products by Attribute work with PHP templates

[Aljullu]

Currently, it's not possible to use the Filter Products by Attribute block with PHP templates. That's because that block is designed to only work with the All Products block.

This issue is about updating it, so it can work with the Shop catalog template.

To reproduce

1. With a block theme, go to Appearance > Editor > Template > Product Catalog.
2. Add the Filter Products by Attribute block above the product grid.
3. Change the selected values in the filter block
4. Notice the products in the product grid don't update.

Expected behavior

The products in the product grid should update based on the selected filters.