Unable to include folder/dir as deps in elyra pipeline from node properties.

[harshad16]

Describe the issue
Using elyra plugin to create a pipeline, when trying to introduce the file system as dependencies from node properties.
The inclusion of single files works as expected, however, when trying to include a folder/directory, the elyra sends out an error.
Example:

Error details:
{
  "severity": 1,
  "source": "Elyra Pipeline Validation Service",
  "type": "invalidFilePath",
  "message": "Property has an invalid path to a file/dir or the file/dir does not exist.",
  "data": {
    "nodeID": "8c333f6c-f21f-4061-a00a-098cd80c0f81",
    "nodeName": "test.ipynb",
    "propertyName": "dependencies",
    "value": "/opt/app-root/src/test/test"
  }

To Reproduce
Steps to reproduce the behavior:

1. Create an elyra pipeline.
2. Include some files in a directory and Click on 'node-properties' and then file dependencies
3. include the folder in the dependencies and submit a pipeline.
4. See error

Screenshots or log output

Expected behavior
The folder should be included in the pipeline without many changes.
as it fits these requirements: https://elyra.readthedocs.io/en/stable/user_guide/best-practices-file-based-nodes.html#file-input

Deployment information
Describe what you've deployed and how:

• Elyra version: 3.15.0
• Installation source: PyPI
• Deployment type: Open Data Hub
• Operating system: linux

Related-issue: opendatahub-io/notebooks#215