### Summary

`ansible-galaxy collection install` makes a lot of requests to galaxy.ansible.com and can occasionally hit the rate limit. When that happens, galaxy.ansible.com will return a 520 http code and `ansible-galaxy` fails to download the collection and exits. Ideally when the client encounters a rate limiting http code (either 520, or 429), it should wait, slow down the request rate and try again rather than exiting.

More information is available here: https://github.com/ansible/galaxy/issues/2429 

### Issue Type

Bug Report

### Component Name

ansible-galaxy

### Ansible Version

```console
$ ansible --version
root@ubuntu-s-1vcpu-1gb-nyc3-01:~# ansible --version
ansible 2.10.7
  config file = None
  configured module search path = ['/root/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python3.8/dist-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 3.8.5 (default, Jan 27 2021, 15:41:15) [GCC 9.3.0]
```


### Configuration

```console
$ ansible-config dump --only-changed
root@ubuntu-s-1vcpu-1gb-nyc3-01:~# ansible-config dump --only-changed
root@ubuntu-s-1vcpu-1gb-nyc3-01:~#
```


### OS / Environment

All

### Steps to Reproduce

Run `ansible-galaxy collection install `amazon.aws`. If your internet is fast enough, this will occasionally fail when galaxy.ansible.com returns a 520 error code.

### Expected Results

Collection should be installed.

### Actual Results

```console
`ansible-galaxy` encounters a 429 or 520 http code and exits.
```


### Code of Conduct

I agree to follow the Ansible Code of Conduct


"""Creates an argument spec for working with rate limiting"""
    arg_spec = (dict(
        rate=dict(type='int'),
        rate_limit=dict(type='int'),
    ))
    if spec:
        arg_spec.update(spec)
    return arg_spec
def retry_argument_spec(spec=None):
    """Creates an argument spec for working with retrying"""
    arg_spec = (dict(
        retries=dict(type='int'),
        retry_pause=dict(type='float', default=1),
    ))
    if spec:
        arg_spec.update(spec)
    return arg_spec
def basic_auth_argument_spec(spec=None):
    arg_spec = (dict(
        api_username=dict(type='str'),
        api_password=dict(type='str', no_log=True),
        api_url=dict(type='str'),
        validate_certs=dict(type='bool', default=True)
    ))
    if spec:
        arg_spec.update(spec)
    return arg_spec
def rate_limit(rate=None, rate_limit=None):