### Summary

The `apt_repository` will fail with a somewhat confusing error if gnugp, and dirmngr manager are not installed.  Neither of these packages are Required/Essential/Important, and may not be already installed in minimal systems that you might want to run `apt_repository` on.

The fix might be to just include `gnupg` in the requirements section of the docs.

### Issue Type

Documentation Report

### Component Name

apt_repository

### Ansible Version

```console
$  ansible --version
ansible [core 2.11.4]
  config file = ...
  configured module search path = ...
  ansible python module location = ...
  ansible collection location = ...
  executable location = /usr/local/bin/ansible
  python version = 3.9.2 (default, Feb 28 2021, 17:03:44) [GCC 10.2.1 20210110]
  jinja version = 3.0.1
  libyaml = True
```


### Configuration

```console
$ ansible-config dump --only-changed
```


### OS / Environment

Mostly a docs issue so this is N/A. But apt_repository applies to Debian, Ubuntu, and forks.

### Additional Information

Tells people that need gnupg when using apt_repository.

### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
ansible.builtin.apt_repository:
    repo: deb http://archive.canonical.com/ubuntu hardy partner
    state: absent
- name: Add nginx stable repository from PPA and install its signing key on Ubuntu target
  ansible.builtin.apt_repository:
    repo: ppa:nginx/stable
- name: Add nginx stable repository from PPA and install its signing key on Debian target
  ansible.builtin.apt_repository:
    repo: 'ppa:nginx/stable'
    codename: trusty
- name: One way to avoid apt_key once it is removed from your distro
  block:
    - name: somerepo |no apt key
      ansible.builtin.get_url:
        url: https://download.example.com/linux/ubuntu/gpg
        dest: /etc/apt/trusted.gpg.d/somerepo.asc
    - name: somerepo | apt source
      ansible.builtin.apt_repository:
      repo: "deb [arch=amd64 signed-by=/etc/apt/trusted.gpg.d/somerepo.asc] https://download.example.com/linux/ubuntu {{ ansible_distribution_release }} stable"
      state: present
'''
RETURN = '''#'''
import copy
import glob
import json
import os
import re
import sys
import tempfile
import random