* Use `vars()` instead of directly accessing `__dict__`
* Remove `auto_update` from RareGame's metadata
* Correct check for updating the Steam App ID (We want to keep any changes from the user)
* Collect both Wine and Proton prefixes when removing overlay registry keys.
* Add few convenience functions in config_helper and paths.
Previously the unchanged contents check tested both `key` and `value`
at the same time, so the following case was not accepted.
`ENV_VAR=ENV_VAR`
No matter how unlikely it is for the key to be equal to the value, there
is no reason to restrict it.
For the `key` ("0") column, protecting against existing keys also handles
this case. For the `value` ("1") column, a check has been added.
Using a ChainMap and this custom model, we can display global environ
variables in the per-game settings, allowin better overview and
simpler override.
