Add support for custom environment files in TripleO and Standalone deployments

[mauricioharley]

This PR adds the ability to specify custom environment files for TripleO and Standalone OpenStack deployments through a new ADDITIONAL_ENV_FILE parameter.

Motivation
Users may need to pass custom environment configurations to their OpenStack deployments without modifying the existing deployment scripts. This enhancement provides a clean, standardized way to inject additional environment files into the deployment process.

Changes

• Makefile: Maps ADDITIONAL_ENV_FILE to deployment-specific variables (TRIPLEO_ADDITIONAL_ENV and STANDALONE_ADDITIONAL_ENV)
• Deployment scripts:
  • Export the environment variables
  • Conditionally copy additional environment files to target systems via SCP
  • Include them in deployment commands using the -e flag when present

Usage

# For TripleO deployment
make tripleo_deploy ADDITIONAL_ENV_FILE=/path/to/custom-env.yaml

# For Standalone deploymentmake 
standalone_deploy ADDITIONAL_ENV_FILE=/path/to/custom-env.yaml

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