Separated test engine configuration from the actual application JSON

[apandura-tibco]

feat(server): Added support to engine configuration file for local engine.

• Added a new app config property defaultFlogoEngineConfigPath
• Users can set environment variable FLOGO_WEB_DEFAULT_ENGINE_CONFIG to set the path to default engine config
• Users can provide a different path while updating the engine config

Description

The latest flogo core provides support to maintain different engine configuration files which will be allow us to build the flogo-web's local engine binary with different test configurations.

How has this been tested?

Manual testing.

1. Should not effect the new engine creation while the server start up
2. The telemetry service must be installed to the local engine through this engine config file
3. Should maintain a engine.json file in local engine's folder before building the local engine

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)
• [X] Refactoring (no functional changes, no api changes)
• [ ] Build/CI related changes
• [ ] Documentation related changes
• [ ] Other... Please describe:

Checklist:

• [X] My code follows the code style of this project.
• [X] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.