'copy' write new line at end of file if 'content' passed without newlin...

...e.

POSIX states that a file should end by a newline.
http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_206

For previous discussion/github issue, refer to https://github.com/ansible/ansible/pull/8528 / https://github.com/adamchainz/ansible/commit/842a1b976d650b2c3117a6e0ed1329e5d0d62873 and https://github.com/ansible/ansible/issues/7855