### Summary

To reproduce, run these commands where `ns.col` is the name of a collection you do not have installed and the value of `-p` is a valid collection path that exists:

`ansible-galaxy collection list ns.col -p collections/`
`$?`

The output of $? on devel is 0, but since the collection wasn't found it should be 1. The same issue exists for listing specific roles that do not exist.

To fix:
1. [This method](https://github.com/ansible/ansible/blob/stable-2.14/lib/ansible/cli/galaxy.py#L1494-L1502) needs to return the correct exit code from `execute_list_role` and `execute_list_collection`.

2. `execute_list_collection` and `execute_list_role` will need to be fixed to return 1 if a collection/role was requested and not found.
For example, on [this line ](https://github.com/ansible/ansible/blob/stable-2.14/lib/ansible/cli/galaxy.py#L1680) add
```python
        if not collection_found and collection_name:
            return 1
```

3. Add a new test to [this file](https://github.com/ansible/ansible/blob/stable-2.14/test/integration/targets/ansible-galaxy-collection/tasks/list.yml), similar to [this one](https://github.com/ansible/ansible/blob/stable-2.14/test/integration/targets/ansible-galaxy-collection/tasks/list.yml#L111-L116) that lists a single collection that does not exist. Then add an assert task following it to test that the command result's rc is 1.

4. Add a `bugfixes` [changelog fragment](https://docs.ansible.com/ansible/latest/community/development_process.html#creating-a-changelog-fragment).

### Issue Type

Bug Report

### Component Name

ansible-galaxy

### Ansible Version

```console
$ ansible --version
ansible [core 2.15.0.dev0]
```


### Configuration

```console
# if using a version older than ansible-core 2.12 you should omit the '-t all'
$ ansible-config dump --only-changed -t all
```


### OS / Environment

N/A

### Steps to Reproduce

<!--- Paste example playbooks or commands between quotes below -->
```bash (paste below)
ansible-galaxy collection list ns.col -p collections/
$?
```

### Expected Results

1

### Actual Results

```console
0
```


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
install_items, requirements_file,
                signatures=signatures,
                artifacts_manager=artifacts_manager,
            )
            collection_requirements = requirements['collections']
            if requirements['roles']:
                display.vvv(two_type_warning.format('role'))
        else:
            if not install_items and requirements_file is None:
                raise AnsibleOptionsError("- you must specify a user/role name or a roles file")
            if requirements_file:
                if not (requirements_file.endswith('.yaml') or requirements_file.endswith('.yml')):
                    raise AnsibleError("Invalid role requirements file, it must end with a .yml or .yaml extension")
                galaxy_args = self._raw_args
                will_install_collections = self._implicit_role and '-p' not in galaxy_args and '--roles-path' not in galaxy_args
                requirements = self._parse_requirements_file(
                    requirements_file,
                    artifacts_manager=artifacts_manager,
                    validate_signature_options=will_install_collections,
                )
                role_requirements = requirements['roles']
                
                
                if requirements['collections'] and (not self._implicit_role or '-p' in galaxy_args or
                                                    '--roles-path' in galaxy_args):
                    
                    
                    display_func = display.warning if self._implicit_role else display.vvv
                    display_func(two_type_warning.format('collection'))
                else: