feat: add environment variables to configure monitoring in Docker image

[Masterchen09]

I saw that the CLI of datahub-actions contains an option to enable a monitoring endpoint - this PR introduces two new environment variables (DATAHUB_ACTIONS_MONITORING_ENABLED and DATAHUB_ACTIONS_MONITORING_PORT) which allows to enable this endpoint when running the Docker image.

There will be a second PR for the datahub-helm repository which will make use of these two environment variables.

edit: Here is the other PR: https://github.com/acryldata/datahub-helm/pull/473

[github-actions[bot]]

Unit Test Results (build & test)

63 tests  ±0   63 :heavy_check_mark: ±0   3s :stopwatch: -1s   1 suites ±0     0 :zzz: ±0    1 files   ±0     0 :x: ±0 

Results for commit 2d964bff. ± Comparison against base commit 54a568b5.

[sgomezvillamor]

I also need to set --enable-monitoring flag, so +1 to this PR and the corresponding one in the helm charts

[jjoyce0510]

Thank you!