Fix up companion.Session.close() refactor

* When PyCharm made a mess I accidentally undid two renames in
  EDMarketConnector.py...
* ... but one of those actually *does* need to only close the session.  So
  made a new Session.close() that performs only the closing, with
  Session.reinit_session() now utilising that.

EDMarketConnector.py

@@ -1253,7 +1253,7 @@ class AppWindow(object):
 
         except companion.CredentialsRequireRefresh:
             # We need to 'close' the auth else it'll see STATE_OK and think login() isn't needed
-            companion.session.close()
+            companion.session.reinit_session()
             # LANG: Frontier CAPI Access Token expired, trying to get a new one
             self.status['text'] = _('CAPI: Refreshing access token...')
             if companion.session.login():

companion.py

@@ -732,6 +732,14 @@ class Session(object):
             self.auth = None
             raise  # Bad thing happened
 
+    def close(self) -> None:
+        """Close the `request.Session()."""
+        try:
+            self.requests_session.close()
+
+        except Exception as e:
+            logger.debug('Frontier Auth: closing', exc_info=e)
+
     def reinit_session(self, reopen: bool = True) -> None:
         """
         Re-initialise the session's `request.Session()`.
@@ -739,11 +747,7 @@ class Session(object):
         :param reopen: Whether to open a new session.
         """
         self.state = Session.STATE_INIT
-        try:
-            self.requests_session.close()
-
-        except Exception as e:
-            logger.debug('Frontier Auth: closing', exc_info=e)
+        self.close()
 
         if reopen:
             self.requests_session = requests.Session()