feat: let zarf packages define requirements

[Shasties]

Description

Full disclosure upfront that Claude did all of the heavy lifting for building the tests.

Currently, there is no visibility into what a zarf package needs to successfully deploy. This is burdensome on developers who have to use some sort of onBefore action or pre-req component to validate things, and it is burdensome to admins+operators who only learn partially through a deployment if a dependency is missing. This PR seeks to help bridge that gap and provide the option to insert REQUIREMENTS files into their zarf package.

I built and tested this on a windows machine, seems to function good enough in my local environment but obviously needs more eyes. Should probably be extended in the future with features like:

1. zarf package list-requirements x to display requirements of a package ahead of time.
2. Currently, developers specify the path to the tooling. This obviously isn't the right paradigm. Something like zarf package deploy --alternate-req=custom-binary=/some/other/path should be introduced so the developers focus on what tool is required for a package to work, while the operator can focus on how to make that tooling available.
   ...

Related Issue

Fixes #4605

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[a1994sc]

Two little comments.

I think that this is the right direction to go if we want to truly be the "Package Manager for Kubernetes", then we should package version validation before deploying the packages.

[a1994sc]

I think that this file should be named requirements.yaml for 2 reasons:

• if this is going need to be a yaml file, the file extension should reflect that.
• we currently don't have any other files will all upper case

[Shasties]

That's a fair point. When I was originally thinking about what the requirements file looked like, I wasn't sure if it should be json/yaml/other, so I left it as REQUIREMENTS. I can update that to requirements.yaml.