Miscellaneous updates based on feedback

[cormacpayne]

This PR resolves the following items:

• Location : Canada Central container-apps-deploy-action#17
  • Introduces the location argument to specify the region that the Container App will be deployed to
  • Added documentation for this argument to call out how to find valid locations
• Does AzureContainerAppsRC task support sending Environment Variables along with build Image? #4
  • Introduces the environmentVariables argument to specify a list of environment variables to set on the deployed Container App
  • Originally introduced by @Basssiiie in PR Allow passing environment variables in AzureContainerAppsV0 task microsoft/azure-pipelines-tasks#17595
• Cannot run AzureContainerAppsV0 tasks on Win32 agents #6
  • Handles the OS of the agent that is executing the Azure DevOps Task to account for commands are executed and how the pack CLI is installed
  • Originally introduced by @icornett in PR add windows support for container tasks #5
• Why task is downloading aditional code? #3
  • Improves documentation to call out how the pack CLI is being installed by the task
• Improves validation for provided arguments
• Improves argument documentation and examples

[pauld-msft]

one take it or leave it nit but other than that LGTM