[FEAT REQ] Support `user` argument in Action YAML when `using: 'docker'`

Describe the enhancement

I have a Dockerfile that specifies a USER. As discussed in #1214, a USER specified in the Dockerfile causes a GitHub Action to fail.

I can't help but notice the Action YAML accepts several docker run argument names (e.g. entrypoint, env, etc...). If it were to also accept user, then I could override the USER definition in the Dockerfile and run the container as the root user. This would allow the runner to make the necessary folders, and also provide an acceptable workaround for issue #1214.

For the CI, it doesn't matter much if the root user builds and "owns" all the resulting files. However, when I run the container locally, it makes my local file system require elevated privileges to clean up build artifacts. While it's true that I can specify a different user on the command line when I build locally, it would be better if this was handled by the runner. If the runner specifies the root user, then it's codified in YAML and does not have to be considered at each invocation.

Code Snippet

name: 'Build'
description: 'Build using CMake and the ARM toolchain'
runs:
  using: 'docker'
  image: '../../../Dockerfile'
  user: 'root'
  entrypoint: 'sh'
  args:
    - '-c'
    - 'rm -rf build/ && mkdir build && cd build/ && cmake -DSPARROW_LORA_ONLY=1 .. && make -j'

Additional information
Add any other context about the feature here.

NOTE: if the feature request has been agreed upon then the assignee will create an ADR. See docs/adrs/README.md

Start by reviewing the existing Docker-related Action YAML arguments described in the issue and the context of issue #1214. Check docs/adrs/README.md for the repository's feature-request process, then trace where arguments such as entrypoint and env are handled. Done means a docker action can accept user: 'root' and the behavior is covered by appropriate tests.