closes#11990
- access should be a members feature, but it was already accidentally exposed to the theme layer
- it has now been added to the API even if members is disabled
- access defaults to true, unless members is enabled
- when members is enabled, access is set to the currently logged in members' access
- move all test files from core/test to test/
- updated all imports and other references
- all code inside of core/ is then application code
- tests are correctly at the root level
- consistent with other repos/projects
Co-authored-by: Kevin Ansfield <kevin@lookingsideways.co.uk>