### 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
max_len.append(len(role['username'] + '.' + role['name']))
        name_len = max(max_len)
        format_str = u" %%-%ds %%s" % name_len
        data.append(u'')
        data.append(format_str % (u"Name", u"Description"))
        data.append(format_str % (u"----", u"-----------"))
        for role in response['results']:
            data.append(format_str % (u'%s.%s' % (role['username'], role['name']), role['description']))
        data = u'\n'.join(data)
        self.pager(data)
        return 0
    def execute_import(self):
        """ used to import a role into Ansible Galaxy """
        colors = {
            'INFO': 'normal',
            'WARNING': C.COLOR_WARN,
            'ERROR': C.COLOR_ERROR,
            'SUCCESS': C.COLOR_OK,
            'FAILED': C.COLOR_ERROR,
        }
        github_user = to_text(context.CLIARGS['github_user'], errors='surrogate_or_strict')
        github_repo = to_text(context.CLIARGS['github_repo'], errors='surrogate_or_strict')
        if context.CLIARGS['check_status']:
            task = self.api.get_import_task(github_user=github_user, github_repo=github_repo)
        else:
            
            task = self.api.create_import_task(github_user, github_repo,
                                               reference=context.CLIARGS['reference'],
                                               role_name=context.CLIARGS['role_name'])
            if len(task) > 1: