outputconfigurationstore: add a fallback for when edid parsing fails

When edid parsing fails, KWin will base output settings on the connector, which isn't great on its own, but at least works in many cases. When the edid can be parsed later though (because libdisplay-info has a fix that then reaches the user's distro), the display settings will reset because now the edid identifier is used to exclude the old config (in which the latter is missing).

To work around that, this commit adds output identification based on the edid hash, which is also not ideal, but can be safely matched with in case no output config with a matching edid identifier exists.