[IMP] product,(website_)sale: Product configurator default_get cleanup + bugfix

Targets commit d3530eb0

Purpose
=======

[Follow up AL review]

Removed the default_get override in the sale_order_line model.
- The default values to create records are now specified by pefixing them with "default_" in the JS.
  That will use the built-in framework method, which is more simple/clean.

- The "list_editable_renderer.js" file for the product configurator was removed and its content is now merged within
  the SectionAndNoteListRenderer.

Updated fields:

- [sale_order_line in sale/sale.py] "product_no_variant_attribute_values" to "product_no_variant_attribute_value_ids"

[Follow up JCR testing]

Various bug fixes including:

- optional products dont show when they have variants configured on them
- when no variant is created, you cant choose the product one first time in the ecommerce
- when in debug, attribute and attribute value menu is double
- fix design of default picture in cart summary / product comparison
- fix missing href tag on product comparison "add to cart" buttons
- fix button "Configure Variants" is always shown even if there are no variants