### 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
"""
        Exits with the specified return code unless the
        option --ignore-errors was specified
        """
        if not context.CLIARGS['ignore_errors']:
            raise AnsibleError('- you can use --ignore-errors to skip failed roles and finish processing the list.')
    @staticmethod
    def _display_role_info(role_info):
        text = [u"", u"Role: %s" % to_text(role_info['name'])]
        
        galaxy_info = role_info.get('galaxy_info', {})
        description = role_info.get('description', galaxy_info.get('description', ''))
        text.append(u"\tdescription: %s" % description)
        for k in sorted(role_info.keys()):
            if k in GalaxyCLI.SKIP_INFO_KEYS:
                continue
            if isinstance(role_info[k], dict):
                text.append(u"\t%s:" % (k))
                for key in sorted(role_info[k].keys()):
                    if key in GalaxyCLI.SKIP_INFO_KEYS:
                        continue
                    text.append(u"\t\t%s: %s" % (key, role_info[k][key]))
            else:
                text.append(u"\t%s: %s" % (k, role_info[k]))
        
        text.append(u"")
        return u'\n'.join(text)
    @staticmethod
    def _resolve_path(path):