[18.0][ADD] product_supplierinfo_active_products_performance_filter

[StephaneMangin]

Summary

Adds a new module product_supplierinfo_active_products_performance_filter that
fixes a severe performance regression on the Active Products search filter in
Purchase → Configuration → Vendor Pricelists.

Fixes upstream issue: odoo/odoo#106058

Problem

The standard Active Products filter uses the domain:

['|', ('product_tmpl_id.active', '=', True), ('product_id.active', '=', True)]

On databases with millions of products, PostgreSQL cannot satisfy this with an
index on product.supplierinfo (no local active column) and falls back to a
full-table scan — causing queries that run for more than 10 minutes.

Solution

Denormalizes product.active onto product.supplierinfo as a stored, indexed
boolean field is_product_active. The filter domain becomes:

[('is_product_active', '=', True)]

The field is kept in sync via ORM hooks on product.template and
product.product. A post_init_hook backfills existing rows on install using
direct SQL for performance.