Add configurable file size limits to the Conan package repository

Problem

The current file size limit when publishing a Conna package to the GitLab package registry is hardcoded as 50MB

Solution

An admin user can set a maximum file size for Conan package files for the instance in the admin package settings section.

The default setting should be 50MB.

Technical notes

Create a plan_limits column named conan_max_file_size to manage this setting

References

Investigation of package limits