DataDirectProcessor: Add logging when file opens fail

Fixes #12251.

Signed-off-by: Paul Harrison <pharrison@mythtv.org>
(cherry picked from commit f4634d2ea524baf2e7c2d99995b7b565e635cd07)
DataDirectProcessor: Use random temporary filenames for downloads

Fixes #12253.

Signed-off-by: Paul Harrison <pharrison@mythtv.org>
(cherry picked from commit 299141e0a69b706239beb35b096df9ed2cea8a7b)

Conflicts:
	mythtv/libs/libmythtv/datadirect.cpp