Allow me to specify that a variable value must be present to proceed with install

[JoeHCQ1]

Is your feature request related to a problem? Please describe.

Right now, if I want to mandate a variable I must create a regex pattern that rejects the empty string. While this achieves the needed functionality, as a non-go programmer, this slows me down plenty. It'd be much simpler if I could just specify required: true or optional: false.

Similarly, someone might require a var to be either empty (in which case we use a default value) or that it match a regex. In this case too, it'd be simpler to specify required: true (default is false) than to craft a regex via ChatGPT which allows either blank or a valid input.

Here is the relevant section of the schema: https://github.com/zarf-dev/zarf/blob/main/zarf.schema.json#L122

I expect using the keyword required is better because the default behavior is required: false. I think it's more intuitive for optional fields to default false than true so the field should be named required not optional.