feat(system-info): expose rhodecode config for better visibility of set settings

fix(permissions): added a common way to update private flag via repo model - this allows to have a one and only one way to control the flag with the business logic shared - added test for that - changed view to use this method instead of DB update and custom permissions flush - fixed a case when update of repo settings didn't flush permissions actually while it should when private flag changed

fix(permissions): fixed security problem with apply-to-children functionality breaking permissions for private repositories fixes: RCCE-141

fix(tests): explicitly disable env_expand for test suite to prevent problems with DB connections during tests

release: Bump version 5.2.0 to 5.3.0

Added tag v5.2.0 for changeset 50cf7822bd80

chore: fixed merge conflicts

chore: fixed release notes for 5.2.0

chore: filled release notes for 5.2.0

chore: disabled audit functionality for now