Create initial openedx/envs/common.py #36889

The end goal of the parent epic is to have this settings structure: https://github.com/openedx/edx-platform/blob/master/docs/decisions/0022-settings-simplification.rst#target-settings-structure-for-edx-platform. In particular, we want an openedx/envs/common which includes all settings definitions shared by LMS and CMS.

We will not get to the full goal in this ticket. It'll take some time to figure out how to factor out the full list of settings that LMS and CMS share without accidentally changing any LMS or CMS setting values. Instead, we'll start with a list of known shared settings (described below).

For this ticket:

• Create openedx/envs/common.py
• Include a comment explaining what the file is for, and also explaining that more settings will be moved there over time
• Look at the list of settings that cms/envs/common imports from lms/envs/common: https://github.com/openedx/edx-platform/blob/master/cms/envs/common.py#L54. These are the shared settings which we'll factor out for this ticket.
  • Move those settings' definitions and annotations from lms/envs/common into openedx/envs/common
  • Change cms/envs/common to import from openedx/envs/common instead of lms/envs/common
  • cms/envs/common should not longer import anything from lms/envs/common
• Ensure that the settings in openedx/envs/common.py still end up in the settings reference. Run make docs to generate this locally.
• See general testing instructions notes in the parent PR. The output of the rendered settings should not change.