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/lookup/file.py

@@ -19,6 +19,7 @@ __metaclass__ = type
 
 from ansible.errors import AnsibleError, AnsibleParserError
 from ansible.plugins.lookup import LookupBase
+from ansible.module_utils._text import to_text
 
 try:
     from __main__ import display
@@ -41,7 +42,8 @@ class LookupModule(LookupBase):
             display.vvvv(u"File lookup using %s as file" % lookupfile)
             try:
                 if lookupfile:
-                    contents, show_data = self._loader._get_file_contents(lookupfile)
+                    b_contents, show_data = self._loader._get_file_contents(lookupfile)
+                    contents = to_text(b_contents, errors='surrogate_or_strict')
                     ret.append(contents.rstrip())
                 else:
                     raise AnsibleParserError()