[cloud] Convert s3 module to use boto3 (#21529)

* replace boto with boto3 for the s3 module

make s3 pep8 and remove from legacy files

fix s3 unit tests

* fix indentation

* s3 module - if we can't create an MD5 sum return None and always upload file

* remove Location.DEFAULT which isn't used in boto3 and tidy up the docs

* pep8

* s3: remove default: null, empty aliases, and required: false from documentation

fix incorrectly documented defaults

* Porting s3 to boto3. Simplify some logic and remove unused imports

* Fix s3 module variables

* Fix a typo in s3 module and remove from pep8 legacy files

* s3: add pagination for listing objects.

Fix logic and use head_object instead of get_object for efficiency.

Fix typo in unit test.

* Fix pagination to maintain backwards compatibility.

Fix incorrect conditional.

Remove redundant variable assignment.

Fix s3 list_object pagination to return all pages

* Use the revised List Objects API as recommended.

* Wrap call to paginated_list in a try/except

Also remembered to allow marker/prefix/max_keys to modify what keys are listed

* Simplify argument

test/units/modules/cloud/amazon/test_s3.py

@@ -1,10 +1,11 @@
 import pytest
+
 import unittest
 
 import ansible.modules.cloud.amazon.s3 as s3
 from ansible.module_utils.six.moves.urllib.parse import urlparse
 
-boto = pytest.importorskip("boto")
+boto3 = pytest.importorskip("boto3")
 
 
 class TestUrlparse(unittest.TestCase):
@@ -32,5 +33,5 @@ class TestUrlparse(unittest.TestCase):
         location = None
         rgw = True
         s3_url = "http://bla.blubb"
-        actual = s3.get_s3_connection(aws_connect_kwargs, location, rgw, s3_url)
-        self.assertEqual("bla.blubb", actual.host)
+        actual = s3.get_s3_connection(None, aws_connect_kwargs, location, rgw, s3_url)
+        self.assertEqual(bool("bla.blubb" in str(actual._endpoint)), True)