Add support for string interpolation in runScript file names

[Dambakk]

Proposed changes

Will enable runScript commands to have js string interpolation in their file names. Example:

appId: com.example.app
env:
    SCRIPT_FILE: 125_myScript.js
---
- runScript: 125_myScript.js
- runScript:
      file: ${SCRIPT_FILE}
- runScript: ${ (120 + 5) + '_myScript.js' }
- evalScript: ${ output.somePath = "125_myScript.js" }
- runScript: ${ output.somePath }

This change moves some file handling from the orchestra module to the orchestra-models module (including the corresponding InvalidFlowFile exception), to be able to read the script files after the jsEngine has done its magic and applied any string interpolation. This, however, means that any "file not found" issues are now not reported until runtime instead of when the maestro command is ran. After quick discussion with Dan Caseley, we figured this would be an acceptable tradeoff.

Testing

I've added a test to the integration test suite, and built the Maestro CLI locally and tested on some sample flow.

Issues fixed

This change does not fully fix a single issue, but is a partial fix or the beginning on a fix to the following issues:

• Discussing runFlow and runScript: runFlow command's path argument doesn't allow for interpolation of JavaScript values #2012
• Discussing runFlow: [Feature Request] Parameter interpolation should work for runFlow.file #1314