Allow empty values for creds in project and inventory_src

[kk-at-redhat]

SUMMARY

Added an ability to specify empty value for credentials, default_environment and signature_validation_credential in ansible.controller.project module and credentials field in ansible.controller.inventory_source module.

related #14919

ISSUE TYPE

Bug, Docs Fix or other nominal change

COMPONENT NAME

Collection

ADDITIONAL INFORMATION

Suggested testing:

    - ansible.controller.project:
        name: "Creds A"

    - ansible.controller.project:
        name: "Creds A"
        credential: "GitHub A"
        default_environment: "Control Plane Execution Environment"
        signature_validation_credential: "GPG"

    - ansible.controller.project:
        name: "Creds A"
        credential: None
        default_environment: None
        signature_validation_credential: None

    - ansible.controller.project:
        name: "Creds A"
        credential: "GitHub A"
        default_environment: "Control Plane Execution Environment"
        signature_validation_credential: "GPG"

    - ansible.controller.project:
        name: "Creds A"
        credential: ""
        default_environment: ""
        signature_validation_credential: ""


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

    - ansible.controller.inventory_source:
        name: "A"
        inventory: "Dynamic A"
        credential: "Custom A"

    - ansible.controller.inventory_source:
        name: "A"
        inventory: "Dynamic A"
        credential: None

    - ansible.controller.inventory_source:
        name: "A"
        inventory: "Dynamic A"
        credential: "Custom A"

    - ansible.controller.inventory_source:
        name: "A"
        inventory: "Dynamic A"
        credential: ""