Read env vars from agent configs

[VirxEC]

This example now works from the gui when added outside the botpack:

[details]
description = ""
developer = "The RLBot community"
fun_fact = "Made with GigaLearn"
language = "C++"
source_link = ""
tags = ["1v1", "teamplay"]

[settings]
agent_id = "VirxEC/Veai/ggl"
loadout_file = "loadout.toml"
logo_file = "logo.png"
name = "Veai (GGL)"
run_command = 'x86_64-pc-windows-msvc\\GGLBot.exe'
run_command_linux = "x86_64-unknown-linux-gnu/GGLBot"
environment = { "LD_LIBRARY_PATH" = "/home/virx/.local/share/RLBot5/bots/torch-archive/torch/lib/" }