Werk #11711: mk_logwatch: Fix plugin execution on Windows

If the mk_logwatch agent plugin was used no Agent Output was created and the HW-/SW Inventory would fail aswell. Therefore the agent plugin could not be used for Windows.

The reasons for that were:

• In Python 3 sys.stdout returns `\r\n` as linebreak for Windows. Checkmk can't handle this therefore we removed it by replacing the default sys.stdout.
• The win32api module could not be imported because pywin32 was not installed. Now pywin32 is installed by default.

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