Add ability to open files with password protection

[flaminestone]

Some files have password protection, and can't be opened in editors via test-examples.
If I try to open file with protection, I see a conversion error and log notes in documentserver-example:

{ message: 'Error occurred in the ConvertService: Error unexpected guid' }

It will be good to add the ability to open files with password protection, or at least logs about unavailability of the feature

Attach protection file for example (pw - 12345
example.zip

)