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/parsing/dataloader.py

@@ -116,7 +116,9 @@ class DataLoader():
             parsed_data = self._FILE_CACHE[file_name]
         else:
             # read the file contents and load the data structure from them
-            (file_data, show_content) = self._get_file_contents(file_name)
+            (b_file_data, show_content) = self._get_file_contents(file_name)
+
+            file_data = to_text(b_file_data, errors='surrogate_or_strict')
             parsed_data = self.load(data=file_data, file_name=file_name, show_content=show_content)
 
             # cache the file contents for next time
@@ -178,7 +180,6 @@ class DataLoader():
                     data = self._vault.decrypt(data, filename=b_file_name)
                     show_content = False
 
-            data = to_text(data, errors='surrogate_or_strict')
             return (data, show_content)
 
         except (IOError, OSError) as e: