Exposes the hide_from_toc xblock attribute so course authors can configure it as a section visibility option in Studio. Before this change, the Hide from TOC functionality was mainly used by OLX components. Hence, it wasn't available for configuration through the Studio UI. Still, its implementation existed in the platform and could be used by setting the attribute: hide_from_toc=true as part of the OLX definition.
Ref: https://openedx.atlassian.net/wiki/spaces/OEPM/pages/3853975595/Feature+Enhancement+Proposal+Hide+Sections+from+course+outline
- Moving xmodule folder to root as we're dissolving sub-projects of common folder in edx-platform
- More info: https://openedx.atlassian.net/browse/BOM-2579
- -e common/lib/xmodule has been removed from the requirements as xmodule has itself become the part of edx-platform and not being installed through requirements
- The test files common/lib/xmodule/test_files/ have been removed as they are not being used anymore
