Parameter for adding dotenv file

[0x20F]

• Provide a way to set env file by number
• Move the current foothold file to ~/.local/carbon-foothold.toml
• Create a new file in /tmp/carbon-emissions.toml and store the running services in there. This'll be the session database
• Provide a way to show indexed env files in a numbered list
• Provide a way to add new env file paths, if parameter isn't provided, check current directory for it and add it to the config as active
• Whenever commands are run, use the active env file as a starting point, unless override parameter is provided
• If parameterr with new env file is provided, add it to the list and set as active