Force user re-authorization for revoked tokens

It's not entirely clear if this is caused by a new condition, the access
is revoked or the error message that canvas emits has change it's
wording.

Logging this situation with the error message to keep track of how often
we see them in the logs.

lms/services/exceptions.py

@@ -1,5 +1,9 @@
+import logging
+
 from lms.models.oauth2_token import Service
 
+log = logging.getLogger(__name__)
+
 
 class JWTError(Exception):
     """A problem with a JWT."""
@@ -215,7 +219,10 @@ def raise_from(cls, cause, request, response, validation_errors=None):
 
         error_description = response_json.get("error_description", "")
 
-        if {"message": "Invalid access token."} in errors:
+        if {"message": "Invalid access token."} in errors or {
+            "message": "Revoked access token."
+        } in errors:
+            log.info("Canvas token error, forcing re-authorization. %s", errors)
             raise OAuth2TokenError(refreshable=True, **kwargs) from cause
 
         if error_description == "refresh_token not found":

tests/unit/lms/services/exceptions_test.py

@@ -186,6 +186,12 @@ class TestCanvasAPIError:
                 json.dumps({"errors": [{"message": "Invalid access token."}]}),
                 OAuth2TokenError,
             ),
+            # A 401 Unauthorized response from Canvas, revoked token
+            (
+                401,
+                json.dumps({"errors": [{"message": "Revoked access token."}]}),
+                OAuth2TokenError,
+            ),
             # A 401 Unauthorized response from Canvas, because our access token had
             # insufficient scopes;
             (