Fix bug (#18355) where encrypted inventories fail 18355 (#18373)

* Fix bug (#18355) where encrypted inventories fail

This is first part of fix for #18355
* Make DataLoader._get_file_contents return bytes

The issue #18355 is caused by a change to inventory to
stop using _get_file_contents so that it can handle text
encoding itself to better protect against harmless text
encoding errors in ini files (invalid unicode text in
comment fields).

So this makes _get_file_contents return bytes so it and other
callers can handle the to_text().

The data returned by _get_file_contents() is now a bytes object
instead of a text object. The callers of _get_file_contents() have
been updated to call to_text() themselves on the results.

Previously, the ini parser attempted to work around
ini files that potentially include non-vailid unicode
in comment lines. To do this, it stopped using
DataLoader._get_file_contents() which does the decryption of
files if vault encrypted. It didn't use that because _get_file_contents
previously did to_text() on the read data itself.

_get_file_contents() returns a bytestring now, so ini.py
can call it and still special case ini file comments when
converting to_text(). That also means encrypted inventory files
are decrypted first.

Fixes #18355

lib/ansible/plugins/action/include_vars.py

@@ -22,7 +22,7 @@ from os import path, walk
 import re
 
 from ansible.errors import AnsibleError
-from ansible.module_utils._text import to_native
+from ansible.module_utils._text import to_native, to_text
 from ansible.plugins.action import ActionBase
 
 
@@ -245,7 +245,9 @@ class ActionModule(ActionBase):
             )
             return failed, err_msg, results
 
-        data, show_content = self._loader._get_file_contents(filename)
+        b_data, show_content = self._loader._get_file_contents(filename)
+        data = to_text(b_data, errors='surrogate_or_strict')
+
         self.show_content = show_content
         data = self._loader.load(data, show_content)
         if not data: