Move access check to hook_file_download

Problem/Motivation

Hello, to support third-party routes that process private files and better compatibility with the kernel, it is better to move the access check to hook_file_download.

This hook is executed by all controllers that want to grant access to a private file. Therefore, user controllers also perform it if they want to check access.

Steps to reproduce

Proposed resolution

Replace the hook_ENTITY_TYPE_access hook for files with the hook_file_download hook.

Remaining tasks

User interface changes

API changes

Data model changes