[hooks] base64-encode extid before inserting it into moved_entities If we insert the wrong value we're never going to find these entities again... Closes #5741105.

[hook] remove assumption about entity cache vs cw_edited We were assuming that if an entity is in the connection's cache, it has a cw_edited attribute. This doesn't seem to always be the case. At least in cubicweb 3.21, merging the web and repo-side caches makes this more likely, but Denis says he's also seen this on 3.20.

[hook] don't open-code Connection.entity_cache