Add a list of previously used release names to make it easy to tell what
release names are no longer usable.
Add a test that new release names have been added to the used list.
Fixes#61616
* Cleanups and version bumping for 2.10
* Fix changelog url now that stable has been branched
* Fix the lenth of the porting guide title now that the version is two digits
After branch, we do the following tasks:
* Remove all old changelog fragments. The devel tree starts fresh.
* Remove all old generated changelog info (CHANGELOG-v2.8.rst and .changes.yaml)
* Set the new codename and version in release.py
* Make ziploader's ansible and ansible.module_utils libraries into
namespace packages.
* Move __version__ and __author__ from ansible/__init__ to
ansible/release.py. This is because namespace packages only load one
__init__.py. If that is not the __init__.py with the author and
version info then those won't be available.
* In ziplaoder, move the version ito ANSIBLE_CONSTANTS.
* Change PluginLoader to properly construct the path to the plugins even
when namespace packages are present.