Expose VARS as environment variables

[yonas]

New boolean variable that exposes variables as environment variables with the same name.

If placed under an individual variable definition, it only affects that variable. If placed directly under vars:, it affects all variables.

I'd like to run a Jinja2 template via minijinja-cli --env ....

The workaround is to simply use env in place of vars, potentially exposing more variables than intended.

Second workaround is to explicitly reference variables when defining the environment variables.