✨ Feature - Auto `.env` file-name detection

[Rikj000]

Closes #34

Description

Gives the option to configure the envFileName as '' (empty string) to auto-detect currently used .env

[Rikj000]

@GeoSot, I manually tested this PR, but can you please write the required test(s) for this or help out with em? :pray:

Already spent a fair amount of time on this project during work hours, and I'm not used to PHPUnit syntax (Been using Pest myself instead)