### 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
role_file = context.CLIARGS['requirements']
        no_deps = context.CLIARGS['no_deps']
        force_deps = context.CLIARGS['force_with_deps']
        force = context.CLIARGS['force'] or force_deps
        for role in requirements:
            
            if role_file and context.CLIARGS['args'] and role.name not in context.CLIARGS['args']:
                display.vvv('Skipping role %s' % role.name)
                continue
            display.vvv('Processing role %s ' % role.name)
            
            if role.install_info is not None:
                if role.install_info['version'] != role.version or force:
                    if force:
                        display.display('- changing role %s from %s to %s' %
                                        (role.name, role.install_info['version'], role.version or "unspecified"))
                        role.remove()
                    else:
                        display.warning('- %s (%s) is already installed - use --force to change version to %s' %
                                        (role.name, role.install_info['version'], role.version or "unspecified"))
                        continue
                else:
                    if not force:
                        display.display('- %s is already installed, skipping.' % str(role))
                        continue
            try:
                installed = role.install()
            except AnsibleError as e:
                display.warning(u"- %s was NOT installed successfully: %s " % (role.name, to_text(e)))