BepInExPack_Valheim version 5.4.2330 needs different Environment Variables

[arrowmaster]

denikson-BepInExPack_Valheim-5.4.2330 is now out which changes from using UnityDoorstop 1.5 to 4.4.0 on Linux. UnityDoorstop 4.x uses new environment variables for configuration.

DOORSTOP_ENABLE is now DOORSTOP_ENABLED and should be set to 1 for enabled or 0 for disabled
DOORSTOP_INVOKE_DLL_PATH is now DOORSTOP_TARGET_ASSEMBLY
DOORSTOP_CORLIB_OVERRIDE_PATH is not used
DYLD_LIBRARY_PATH and DYLD_INSERT_LIBRARIES were never needed as these are only used by MacOS

If you want to support both the new and old UnityDoorstop, it might be possible to set both the new and old variables. But a .doorstop_version file is now included that can be checked to see if the version is greater than 4.

[nbusseneau]

Opening a draft PR for this at #1198, any help/input welcome as I'm not used to Rust.

[mbround18]

@nbusseneau you knocked it out of the park! Awesome contribution! :)