Move in OpenStack credential input helper

This should help decouple credential and inventory plugins.

src/awx_plugins/interfaces/_temporary_private_api.py

@@ -4,6 +4,8 @@
 The hope is that it will be refactored into something more standardized.
 """
 
+from typing import Protocol
+
 
 try:
     # pylint: disable-next=unused-import
@@ -36,4 +38,63 @@ class ManagedCredentialType:  # type: ignore[no-redef]  # noqa: WPS440
         """Flag for whether this plugin instance is managed."""
 
 
+class _CredentialInput(Protocol):
+    def get_input(
+        self: '_CredentialInput',
+        name: str,
+        default: object = None,
+    ) -> bool | str:
+        """Get an input from this credential.
+
+        :param name: Input name to check.
+        :type name: str
+        :param default: Fallback for a missing input.
+        :type default: object
+        """
+
+    def has_input(self: '_CredentialInput', name: str) -> bool:
+        """Check if an input is present.
+
+        :param name: Input name to check.
+        :type name: str
+        """
+
+
+def _retrieve_openstack_data_from_credential(  # noqa: WPS234, WPS320
+        cred: _CredentialInput,
+) -> dict[
+    str,
+    dict[str, dict[str, dict[str, bool | str] | bool | str]],  # noqa: WPS221
+]:
+    openstack_auth = {
+        'auth_url': cred.get_input('host', default=''),
+        'username': cred.get_input('username', default=''),
+        'password': cred.get_input('password', default=''),
+        'project_name': cred.get_input('project', default=''),
+    }
+    if cred.has_input('project_domain_name'):
+        openstack_auth['project_domain_name'] = cred.get_input(
+            'project_domain_name', default='',
+        )
+    if cred.has_input('domain'):
+        openstack_auth['domain_name'] = cred.get_input('domain', default='')
+    verify_state = cred.get_input('verify_ssl', default=True)
+
+    openstack_data = {
+        'clouds': {
+            'devstack': {
+                'auth': openstack_auth,
+                'verify': verify_state,
+            },
+        },
+    }
+
+    if cred.has_input('region'):
+        openstack_data['clouds']['devstack']['region_name'] = cred.get_input(
+            'region', default='',
+        )
+
+    return openstack_data
+
+
 __all__ = ()  # noqa: WPS410