Refactor `charts` definition in `zarf.yaml`

[Racer159]

Describe what should be investigated or refactored

It would be worth taking some time to refactor the charts definition in the zarf.yaml to enhance user understanding of the keys such as repoName and gitPath which are usually non-intuitive for users. repoName really means the name of a chart in a Helm Repo and gitPath means the path of a chart in a git repository which are not obvious to folks not familiar with Zarf.

Links to any relevant code

https://github.com/defenseunicorns/zarf/blob/f039affe91b664f601b274a5e66d29bf030ca75f/src/types/component.go#L92

Additional context

These fields have come up with questions a few times in user questions in our k8s slack.

[AustinAbro321]

propose a schema that looks like below. This is based on the examples/helm-charts within the Zarf repository. Non changed fields were taken out for brevity. Exactly one of the following field will exist for each components.charts.

- name: podinfo-repo-new
  helm:
    url: https://stefanprodan.github.io/podinfo
    name: podinfo # replaces repoName since it's only applicable for helm chart repositories
    version: 6.4.0

- name: podinfo-git-new
  git:
    url: https://stefanprodan.github.io/podinfo@6.4.0
    path: charts/podinfo
    # no version field, use chart.yaml version field at that git tag

- name: podinfo-oci-new
  oci:
    url: oci://ghcr.io/stefanprodan/charts/podinfo
    version: 6.4.0

- name: podinfo-local-same
  local:
   path: chart
    # no version field, use local chart.yaml version