feat: native helm support

[xopham]

Fixes no issue

Description

• helm values, Chart, and templates are refactored/improved to provide more native helm support and improve usability
• helm and app versioning are properly seperated

⚠️ WIP NOTES:

• Discuss using appVersion as v2.2.0 instead of 2.20
• Consider further version definitions e.g. k8s
• ADR 8 on Helm versioning
• docs
  • new quick start
  • new getting started
  • add versioning notes on start page
• cleanup helm/values.yaml (adjust defaults, take out examples)
• add improvements by @annekebr

Checklist

• PR is rebased to/aimed at branch develop
• PR follows Contributing Guide
• Added tests (if necessary)
• Extended README/Documentation (if necessary)
• Adjusted versions of image and Helm chart in values.yaml and Chart.yaml (if necessary)

[codecov-commenter]

Codecov Report

Merging #430 (2eba1d4) into develop (bf4de6f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #430   +/-   ##
========================================
  Coverage    94.47%   94.47%           
========================================
  Files           22       22           
  Lines         1105     1105           
========================================
  Hits          1044     1044           
  Misses          61       61           

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[phbelitz]

no longer applicable with golang switch