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##### SUMMARY
The "source" folder of my collection contains several files that are not directly related to the collection itself. E.g. a `.gitignore`, a `.github` folder, a `Makefile` etc.
When using `ansible-galaxy collection build <folder>`, these files are included in the generated tarball. This is especially hurtful when the source folder also contains a Python venv that I use for developing.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
ansible-galaxy

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.9.0.dev0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/home/egolov/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /home/egolov/Devel/ansible/ansible/lib/ansible
  executable location = /home/egolov/Devel/ansible/ansible/bin/ansible
  python version = 2.7.15 (default, Oct 15 2018, 15:26:09) [GCC 8.2.1 20180801 (Red Hat 8.2.1-2)]

```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
empty
```

##### OS / ENVIRONMENT
Fedora


##### STEPS TO REPRODUCE
Build a collection :)

##### EXPECTED RESULTS
I'd expect only collection-relevant files/folders (those that are listed in the spec/docs) to be included.


##### ADDITIONAL INFORMATION
Alternatively, a ignore file as suggested by @bcoca  in https://github.com/ansible/ansible/pull/59121/files#r304554334 could be a fix for this.

"""
        Perform the action on an Ansible Galaxy role. Must be combined with a further action like delete/install/init
        as listed below.
        """
        
        pass
    def execute_collection(self):
        """
        Perform the action on an Ansible Galaxy collection. Must be combined with a further action like init/install as
        listed below.
        """
        
        pass
    def execute_build(self):
        """
        Build an Ansible Galaxy collection artifact that can be stored in a central repository like Ansible Galaxy.
        By default, this command builds from the current working directory. You can optionally pass in the
        collection input path (where the ``galaxy.yml`` file is).
        """
        force = context.CLIARGS['force']
        output_path = GalaxyCLI._resolve_path(context.CLIARGS['output_path'])
        b_output_path = to_bytes(output_path, errors='surrogate_or_strict')
        if not os.path.exists(b_output_path):
            os.makedirs(b_output_path)
        elif os.path.isfile(b_output_path):
            raise AnsibleError("- the output collection directory %s is a file - aborting" % to_native(output_path))
        for collection_path in context.CLIARGS['args']:
            collection_path = GalaxyCLI._resolve_path(collection_path)
            build_collection(collection_path, output_path, force)
    def execute_init(self):