[Feature]: `corefunc_dotenv_decode`

[skyzyx]

What functionality would you like to see?

data corefunc_dotenv_decode "dotenv" {
  file = file(".env")
}
#=> map(string)

Problem

• Request: Enable simple/native way to read .env files hashicorp/terraform#23906
• --from-env-file Implementation to kubernetes_secret resource hashicorp/terraform-provider-kubernetes#889

References

https://github.com/motdotla/dotenv
https://github.com/vlucas/phpdotenv
https://pypi.org/project/python-dotenv
https://github.com/joho/godotenv
https://github.com/direnv/go-dotenv
https://github.com/cdimascio/java-dotenv
https://12factor.net/config