Allow empty values for source_project in inventory_source

[kk-at-redhat]

SUMMARY

Added an ability to specify empty value for source_project in ansible.controller.inventory_source module.

related #14921

ISSUE TYPE

Bug, Docs Fix or other nominal change

COMPONENT NAME

Collection

ADDITIONAL INFORMATION

Suggested testing:

    - ansible.controller.inventory_source:
        name: "A"
        inventory: "Dynamic A"
      ignore_errors: true

    - ansible.controller.inventory_source:
        name: "A"
        inventory: "Dynamic A"
        source: scm
        source_project: "Creds A"
      ignore_errors: true

    - ansible.controller.inventory_source:
        name: "A"
        inventory: "Dynamic A"
        source: ec2
        source_project: ""
      ignore_errors: true

    - ansible.controller.inventory_source:
        name: "A"
        inventory: "Dynamic A"
        source: ec2
        source_project: {}
      ignore_errors: true

    - ansible.controller.inventory_source:
        name: "A"
        inventory: "Dynamic A"
        source: ec2
        source_project: None
      ignore_errors: true