Fix general settings environment variables resolution

[antirotor]

Fix

Fix how variables are resolved in general settings. This will now allow to define new variables and resolve them in one pass.

For example:

{
    "FOO": "something",
    "BAR": ["{FOO}", "else"]
}

will now resolve correctly. This was crashing OpenPype on start.

Resolves #3585

[ynbot]

Task linked: OP-3658 Environment variables config bug on Windows