Remove local copy of openedx-chem package

now that we install it from an external repository.

docs/conf.py

@@ -27,7 +27,6 @@ sys.path.append(root / "docs")
 sys.path.append(root / "cms/djangoapps")
 sys.path.append(root / "common/djangoapps")
 sys.path.append(root / "common/lib/capa")
-sys.path.append(root / "common/lib/chem")
 sys.path.append(root / "common/lib/safe_lxml")
 sys.path.append(root / "common/lib/symmath")
 sys.path.append(root / "common/lib/xmodule")
@@ -236,7 +235,6 @@ autodoc_mock_imports = [
 modules = {
     'cms': 'cms',
     'common/lib/capa/capa': 'common/lib/capa',
-    'common/lib/chem/chem': 'common/lib/chem',
     'common/lib/safe_lxml/safe_lxml': 'common/lib/safe_lxml',
     'common/lib/symmath/symmath': 'common/lib/symmath',
     'common/lib/xmodule/xmodule': 'common/lib/xmodule',

docs/docstrings/common_lib.rst

@@ -9,7 +9,6 @@ out from edx-platform into separate packages at some point.
     :maxdepth: 2
 
     common/lib/capa/modules
-    common/lib/chem/modules
     common/lib/safe_lxml/modules
     common/lib/symmath/modules
     common/lib/xmodule/modules