Feature: #103522 - Page TSconfig provider for sites and sets

See forge#103522

Description

TYPO3 sites have been enhanced to be able to provide page TSconfig on a per-site basis.

Site page TSconfig is loaded from page.tsconfig, if placed next to the site configuration file config.yaml and is scoped to pages within that site.

Impact

Sites and sets can ship page TSconfig without the need for database entries or by polluting global scope when registering page TSconfig globally via ext_localconf.php or Configuration/page.tsconfig. Dependencies can be expressed via sets, allowing for automatic ordering and deduplication.