feat(docker): Refactor Dockerfile

[duhow]

• Reduce build layers from 23 to 12
• Add ARG PHP_VERSION to allow usage of different php versions (defaults to 8.1)
• Reorder layers to allow common content to be reusable (layers) between different builds

Ideally composer can be in a separate RUN way, so if dependencies do not change, it can keep the same content from other builds, but I'm unable to setup this at the moment.

[jbtronics]

Thank you. Looks good, I will review (and try it out) in detail later.

Maybe some of the changes can also be applied to the frankenphp Dockerfile (https://github.com/Part-DB/Part-DB-server/blob/master/Dockerfile-frankenphp), because in long term I would like to make the frankenphp version the default docker image, as the worker model is faster than the classic approach and frankenphp has some other builtin nice features.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.32%. Comparing base (756152d) to head (b7406dc).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #683      +/-   ##
============================================
- Coverage     62.33%   62.32%   -0.02%     
  Complexity     5659     5659              
============================================
  Files           518      518              
  Lines         18708    18708              
============================================
- Hits          11662    11659       -3     
- Misses         7046     7049       +3     

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