fix(anta.cli): Use configured anta inventory as output by default in get from-ansible

[titom73]

Description

Use configured anta inventory if --output is not configured in anta get from-ansible command.

anta get from-ansible --ansible-inventory ../anta-lab/atd-inventory/inventory.yml
[19:02:09] INFO     Building inventory from ansible file ../anta-lab/atd-inventory/inventory.yml
[19:02:12] INFO     output anta inventory is: anta-lab/network-tests/inventory.yml
           INFO        * adding entry for cv_atd1
           INFO        * adding entry for spine1
           INFO        * adding entry for spine2
           INFO        * adding entry for leaf1 
           INFO        * adding entry for leaf2 
           INFO        * adding entry for leaf3
           INFO        * adding entry for leaf4
           INFO     ANTA device inventory file has been created in anta-lab/network-tests/inventory.yml

If destination file has content, then cli asks confirmation to user if he wants to overwrite:

anta get from-ansible --ansible-inventory ../anta-lab/atd-inventory/inventory.yml
[19:07:19] INFO     Building inventory from ansible file ../anta-lab/atd-inventory/inventory.yml
Your destination file (anta-lab/network-tests/inventory.yml) is not empty, continue? [y/n]: n
[19:07:27] CRITICAL conversion aborted since destination file is not empty 

If anta is executed in a non interactive environment, it breaks if destination file has content

To run script in a non-interactive environment, you can use --overwrite to tell anta it can overwrite file with content.

❯ anta get from-ansible --help
Usage: anta get from-ansible [OPTIONS]

  Build ANTA inventory from an ansible inventory YAML file

Options:
  -g, --ansible-group TEXT      Ansible group to filter
  -i, --ansible-inventory FILE  Path to your ansible inventory file to read
  -o, --output FILE             Path to save inventory file. If not
                                configured, use anta inventory file
  --overwrite                   Confirm script can overwrite existing
                                inventory file  [env var:
                                ANTA_GET_FROM_ANSIBLE_OVERWRITE]
  --help                        Show this message and exit.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have run pre-commit for code linting and typing (pre-commit run)
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes (tox -e testenv)

[titom73]

Need to discuss about how to manage a change of the default inventory file
provided

This change is breaking CI in the second run