Add nebari-app library Helm chart for NebariApp CR

[pmeier]

Reference Issues or PRs

Closes #148.

What does this implement/fix?

Put a x in the boxes that apply

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds a feature)
• Breaking change (fix or feature that would cause existing features not to work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Other (please describe):

Testing

• Did you test the pull request locally?
• Did you add new tests?

Documentation

charts/nebari-app/README.md

[github-actions]

Docker Images Built

Images pushed to Quay.io for branch nebari-app-chart:

Image	Tag	Platforms
Operator	quay.io/nebari/nebari-operator:nebari-app-chart	linux/amd64 + linux/arm64

Test the operator:

kubectl apply -k https://github.com/nebari-dev/nebari-operator.git/config/default?ref=nebari-app-chart
kubectl set image deployment/nebari-operator-controller-manager manager=quay.io/nebari/nebari-operator:nebari-app-chart -n nebari-operator-system

[pmeier]

Example downstream implementation in nebari-dev/chat-pack#162