GH-213: enhance WorkspaceUtil to also search in environment variables…

[francoisledroff]

See: #213

Description

As described in the issue, added the possibility to get the configuration for the Workspace from environment variables, which makes it easier to use.

Related Issue

#213
#214

Motivation and Context

Enable the usage of environment variables in docker containers where an entrypoint is defined in exec form, passing the configurations through ENV variables without the need to bind them using the system properties, which turns out to be really cumbersome.

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.