Add role skeleton support (#17079)

* Add role skeleton support

The default role skeleton used by ansible-galaxy is good, but it doesn't
allow organizations to customize it to suit their needs.  This patch
addresses that by adding the option to point ansible-galaxy at a
role skeleton directory.  The contents of this directory are then
copied (or rendered) into the output role directory.  Appropriate
command line options and configuration entries are added to allow for
further customization from the role skeleton.

* Remove dependency on platforms list from test

Platforms are no longer provided to the template by galaxy init.
Removing the code in our test meta/main.yml template that relied on it.

* Fix whitespace issue

test/units/cli/test_data/role_skeleton/README.md

@@ -0,0 +1,38 @@
+Role Name
+=========
+
+A brief description of the role goes here.
+
+Requirements
+------------
+
+Any pre-requisites that may not be covered by Ansible itself or the role should be mentioned here. For instance, if the role uses the EC2 module, it may be a good idea to mention in this section that the boto package is required.
+
+Role Variables
+--------------
+
+A description of the settable variables for this role should go here, including any variables that are in defaults/main.yml, vars/main.yml, and any variables that can/should be set via parameters to the role. Any variables that are read from other roles and/or the global scope (ie. hostvars, group vars, etc.) should be mentioned here as well.
+
+Dependencies
+------------
+
+A list of other roles hosted on Galaxy should go here, plus any details in regards to parameters that may need to be set for other roles, or variables that are used from other roles.
+
+Example Playbook
+----------------
+
+Including an example of how to use your role (for instance, with variables passed in as parameters) is always nice for users too:
+
+    - hosts: servers
+      roles:
+         - { role: username.rolename, x: 42 }
+
+License
+-------
+
+BSD
+
+Author Information
+------------------
+
+An optional section for the role authors to include contact information, or a website (HTML is not allowed).