### 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_exclusive.add_argument('--force-with-deps', dest='force_with_deps', action='store_true', default=False,
                                       help="Force overwriting an existing {0} and its "
                                            "dependencies.".format(galaxy_type))
        valid_signature_count_help = 'The number of signatures that must successfully verify the collection. This should be a positive integer ' \
                                     'or -1 to signify that all signatures must be used to verify the collection. ' \
                                     'Prepend the value with + to fail if no valid signatures are found for the collection (e.g. +all).'
        ignore_gpg_status_help = 'A status code to ignore during signature verification (for example, NO_PUBKEY). ' \
                                 'Provide this option multiple times to ignore a list of status codes. ' \
                                 'Descriptions for the choices can be seen at L(https://github.com/gpg/gnupg/blob/master/doc/DETAILS#general-status-codes).'
        if galaxy_type == 'collection':
            install_parser.add_argument('-p', '--collections-path', dest='collections_path',
                                        default=self._get_default_collection_path(),
                                        help='The path to the directory containing your collections.')
            install_parser.add_argument('-r', '--requirements-file', dest='requirements',
                                        help='A file containing a list of collections to be installed.')
            install_parser.add_argument('--pre', dest='allow_pre_release', action='store_true',
                                        help='Include pre-release versions. Semantic versioning pre-releases are ignored by default')
            install_parser.add_argument('-U', '--upgrade', dest='upgrade', action='store_true', default=False,
                                        help='Upgrade installed collection artifacts. This will also update dependencies unless --no-deps is provided')
            install_parser.add_argument('--keyring', dest='keyring', default=C.GALAXY_GPG_KEYRING,
                                        help='The keyring used during signature verification')  
            install_parser.add_argument('--disable-gpg-verify', dest='disable_gpg_verify', action='store_true',
                                        default=C.GALAXY_DISABLE_GPG_VERIFY,
                                        help='Disable GPG signature verification when installing collections from a Galaxy server')
            install_parser.add_argument('--signature', dest='signatures', action='append',
                                        help='An additional signature source to verify the authenticity of the MANIFEST.json before '
                                             'installing the collection from a Galaxy server. Use in conjunction with a positional '
                                             'collection name (mutually exclusive with --requirements-file).')
            install_parser.add_argument('--required-valid-signature-count', dest='required_valid_signature_count', type=validate_signature_count,
                                        help=valid_signature_count_help, default=C.GALAXY_REQUIRED_VALID_SIGNATURE_COUNT)