##### SUMMARY
If you have executable files in your source code they are not kept in the tarball.

Could be related to https://github.com/ansible/ansible/blob/99d7f150873011e7515851db9b44ff486efa9d77/lib/ansible/galaxy/collection.py#L763

This was noticed as I had some auxiliary scripts in my repo.

Need to also consider scripts in `files/` if/when Collections support roles.

This seems to fail the "principal of least suprise"

**Proposal 1: Keep on stripping executable flags**

Add some line to the output
`WARNING: tests/coverage.sh: source file has executable flag, though this will be ignored in generated tar.gz`
Update developing a collection documentation page
Update integration tests to ensure that executable mode is always stripped.
Update code to link to this issue

**Proposal 2: Allow executible flags**

Update developing a collection documentation page
Update integration tests to ensure that executable mode is preserved
Update code to link to this issue
Changelog


##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
ansible-galaxy

##### ANSIBLE VERSION
```paste below
2.10
```

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

<!--- HINT: You can paste gist.github.com links for larger files -->


@classmethod
    def setUpClass(cls):
        '''creating prerequisites for installing a role; setUpClass occurs ONCE whereas setUp occurs with every method tested.'''
        
        cls.temp_dir = tempfile.mkdtemp(prefix='ansible-test_galaxy-')
        os.chdir(cls.temp_dir)
        if os.path.exists("./delete_me"):
            shutil.rmtree("./delete_me")
        
        gc = GalaxyCLI(args=["ansible-galaxy", "init", "--offline", "delete_me"])
        gc.run()
        cls.role_dir = "./delete_me"
        cls.role_name = "delete_me"
        
        cls.role_path = os.path.join(tempfile.mkdtemp(), "roles")
        if not os.path.isdir(cls.role_path):
            os.makedirs(cls.role_path)
        
        cls.role_tar = './delete_me.tar.gz'
        cls.makeTar(cls.role_tar, cls.role_dir)
        
        cls.role_req = './delete_me_requirements.yml'
        fd = open(cls.role_req, "w")
        fd.write("- 'src': '%s'\n  'name': '%s'\n  'path': '%s'" % (cls.role_tar, cls.role_name, cls.role_path))
        fd.close()
    @classmethod
    def makeTar(cls, output_file, source_dir):