This PR includes documentation that preps for v2 docs (but doesn't introduce new docs).
_Note: The number of file changes in the PR is due to find-and-replace within the `references` which is unavoidable. Let me know if I should move it to another PR._
## Changes
- Change Medusa version in base OAS used for v2.
- Fix to docblock generator related to not catching all path parameters.
- Added typedoc plugin that generates ER Diagrams, which will be used specifically for data model references in commerce modules.
- Changed OAS tool to output references in `www/apps/api-reference/specs-v2` directory when the `--v2` option is used.
- Added a version switcher to the API reference to switch between V1 and V2. This switcher is enabled by an environment variable, so it won't be visible/usable at the moment.
- Upgraded docusaurus to v3.0.1
- Added new Vale rules to ensure correct spelling of Medusa Admin and module names.
- Added new components to the `docs-ui` package that will be used in future documentation changes.
- Fixed CORS middleware to account for routes of a single path (for example, `/custom` and not just `/custom/test`).
- Added a troubleshooting guide for admin webpack errors (see issue #6375)
- Move the original guides for creating endpoints and middlewares to sub-sections in the Endpoints category.
- Replace existing guides for endpoints and middlewares with the new approach.
- Update all endpoints-related snippets across docs to use this new approach.
