Add support for ARTIFACTORY_ACCESS_TOKEN environment variable

[hagenw]

Add the moment a user can provide an password / API key / access token for Artifactory with the ARTIFACTORY_API_KEY environment variable. As API keys are deprecated and will be removed end of 2024, we might think of supporting another environment variable to provide an access token. We could introduce ARTIFACTORY_ACCESS_TOKEN instead. But it is also not ideal, as a user could also provide a password with it. To solve this, we could add another ARTIFACTORY_PASSWORD. But a more meaningful way might be to just add a new variable with a generic name, to cover all possible ways to provide a secret for authentication.